RUVIS: A Device That Allows CSIs to “See” Latent Prints Before Development
The Reflected Ultraviolet Imaging System (RUVIS) was first made available to law enforcement agencies more than a decade ago and is now in use throughout the U.S.A. by Federal, state and municipal agencies, and it has become a valuable aid to governments around the world.
RUVIS derives its uniqueness from the fact that this handheld device permits investigators to actually see latent fingerprints on nonporous surfaces BEFORE any attempt is made to develop them using the traditional methods discussed in previous articles in this series.
The basic theory behind RUVIS is the fact that certain surfaces reflect Shortwave Ultraviolet light, which in itself is invisible. But a RUVIS device changes this.
RUVIS is a two-part system consisting of a portable shortwave UV light and the handheld RUVIS device.
Here’s the basic theory of RUVIS operation:
1. Most nonporous surfaces will either reflect UV light or will absorb it so that no light is reflected. Much depends on the angle that the UV light strikes the surface.
2. The RUVIS device utilizes a specially-constructed lens designed to pass UV light. Most commercially- made camera lenses have features that block UV light, because it interferes with the color balance of the resultant photographs.
3. The RUVIS device is equipped with a “bandpass filter” located behind the lens assembly that blocks all but shortwave UV light—including ambient light in the scene. This permits use in bright sunlight or total darkness. Only the reflected UV light passes through electronic circuitry that amplifies the weak UV light and converts it to visible light—so that it can be seen.
4. Depending on the color and physical nature of the surface being examined, and the angle and distance from the surface that the UV light is positioned, either the background or the moisture of a latent print is seen through the RUVIS device.
5. In the case where the surface is reflecting the light, any latent prints on this surface will absorb the light. The result is that the background will appear as a lighter color on the RUVIS viewing screen while the ridge structure of the latent prints will appear dark in color.
6. A slight change in position will sometimes cause the opposite to occur: the background will be dark and the ridges will be light in color.
Some RUVIS devices permit the direct connection of a camera to the viewer permitting photos of the latent prints to be taken before any attempt is made to develop and lift these prints.
Using a RUVIS device has many benefits both at the crime scene and in the crime lab. Since the user can actually see what is present, he can eliminate the time taken to develop smudges and smears, which have no apparent value. The RUVIS operator can direct his attention to only those prints that may have forensic value.
But another advantage is that recent discoveries make it possible to recover DNA evidence from latent prints, so those CSIs who are collecting DNA evidence can be directed to the smudges and smears instead of collecting useable latents.
Overall, RUVIS saves considerable time that is usually spent in processing an entire crime scene for latent prints.
RUVIS technology is just one example of how law enforcement and private industry have partnered in the war against crime. For more information on this remarkable instrument you are invited to download a FREE CATALOG that covers RUVIS more fully. Click HERE! This catalog may be downloaded by individual sections and RUVIS is found in the third catalog section. You may also download a free copy of: “Overview of latent Print Development Techniques.”
Watch RUVIS locate latent prints without powders or chemicals
Having a problem seeing the video? Watch it on YouTube HERE
Don Penven is a freelance writer and photographer based in Raleigh, NC. He has over 30 years of direct and indirect experience in law enforcement and crime scene investigation.
Part 2 of this series discussed the use of latent print development powders. This article will cover some of the most popular methods of chemical treatments.
Latent print powders are of little use on porous surfaces such as paper, cardboard and raw wood; the reason being that a latent print is over 90% water, which is absorbed and dispersed in the surface. However, if prints are known to be fresh, regular black powder and magnetic powders may produce good results, and use of powders will not interfere with chemical processing. Crime scene investigators (CSIs) are able to recover latent prints from porous surfaces without a great deal of difficulty using chemical methods.
In Part 1 of this series you learned that a latent print is a combination of substances that make up human perspiration (sweat). The sweat pores exude substances like water, amino acid, carbohydrates, choline, proteins and uric acid. The fingertips also deposit oils from contact with areas of the body that harbor sebaceous glands—like on the face, arms and chest.
When examining porous objects like those listed above, the CSI or laboratory technician will follow a specific regimen of tests. Usually the first test is iodine fuming, which we will discuss in a subsequent lesson. Iodine fumes are used first as they are non-destructive to the testing that will follow. But iodine fumes are highly toxic and special care must be exercised when using iodine fuming techniques.
Special Note! All items that are transportable should be taken to the crime lab for processing.
Several chemical reagents are used in many crime labs as they are very sensitive and often produce spectacular results. Let’s take a look at the processing sequence recommended by the FBI and the British Home office. The best order of processing is: Iodine Fuming, DFO, Ninhydrin, and then either Silver Nitrate or Physical Developer. If Ninhydrin is used prior to DFO, the DFO prints will not fluoresce.
Note that DFO and Ninhydrin are a biological stains, and when they react with an amino acid, they exhibit a visible color. Amino acids are a component of sweat and oddly enough they do not disperse into the surface. In fact amino acids form a permanent bond with the cellulose structure of paper, cardboard and raw wood. And this bond conforms to the friction ridge structure of the finger depositing the print.
DFO Treatment
DFO (1,8-Diazafluoren-9-One) is a Ninhydrin analog that reacts to amino acids, but it also has fluorescent properties. Here are the steps to treating a document with DFO: (Author’s Note! It is preferable to run these treatments in the crime lab since it is more efficient and much, much safer when a chemical fume hood [exhaust fan] is available!).
1. Place the object to be treated in a fume hood. In the case of a document, suspend it using evidence clips. Cardboard objects and pieces of wood may be placed on the floor of the fume hood. Be certain to treat all surfaces of each object, since you probably will not know just where latent prints may be found.
2. Spray a heavy coating of the reagent of both sides of the document. Be certain to be wearing latex or nitrile gloves to keep your fingerprints off of the document and to prevent your fingertips from turning color.
3. The document or object should be allowed to air-dry.
DFO Development of a latent palmprint. Examined with Alternate Light Source (ALS) (455nm) and viewed through an orange barrier filter.
4. If tray development is preferred, allow the document to soak for about 5 seconds, just dip and then hang it up to dry.
5. If no other methods are used to accelerate development, it could take several hours or more for latents to develop.
6. Acceleration may be used if available. Expose the document to heat at about 200-degrees. Prints will then pop out in a matter of minutes. Visible DFO prints are often a light pink color, but they usually produce bright fluorescence when exposed to an alternate light source.
7. Once the prints are visible, they must be photographed (with a scale).
After treatment and drying, the document is placed in a heat chamber (at about 200-degrees). The document should remain in the chamber for 5-10 minutes.
After removal from the heat chamber, examine the document under subdued room light using an alternate light source that operates in the range of 455, 470, 505 and 520nm. These light frequencies are available from Sirchie’s BLUEMAXX and megaMAXX alternate light sources. DFO is said to produce 2.5 times the number of latent prints than Ninhydrin.
Ninhydrin Treatment
Ninhydrin is mixed with several different solvents like Xylene or Acetone. Less hazardous formulas are also available since these two are highly flammable. This mixture may be supplied in an aerosol can or a manual pump spray bottle. It is also mixed and used in an open developing tray in the crime lab.
Ninhydrin processing should follow this order:
1. Place the object to be treated in a fume hood. In the case of a document, suspend it using evidence clips. Cardboard objects and pieces of wood may be placed on the floor of the fume hood.
2. Spray a heavy coating of the reagent of both sides of the document object. In the case of objects—be certain to coat all surfaces since you may not know just where latent prints were placed. Be certain to be wearing latex or nitrile gloves to keep your fingerprints off of the document and to prevent your fingertips from turning a purple color.
Ninhydrin. Fully developed Ninhydrin latent print.
3. The document should be allowed to air-dry.
4. If tray development is preferred, allow the document to soak for 5 seconds, just dip and then hang it up to dry.
5. If no other methods are used to accelerate development, it could take 24 hours or more for latents to develop.
6. Acceleration may be used if available. Expose the document to moist heat at about 200-degrees. Prints will then pop out in a matter of minutes. Visible Ninhydrin prints are purple in color. An effective method of acceleration is to apply moist heat from a steam iron. Cover the document with a towel before applying the steam iron to prevent scorching of the document or object.
Even if prints are enhanced using the above methods, re-evaluate the results after waiting about 24 hours.
Ninhydrin prints may fade over a period of time so it may be advisable to use a Ninhydrin fixative (available from most Ninhydrin suppliers).
Alternative Methods
Should both of the above steps fail to produce useable latent prints, two alternative methods are available: Silver Nitrate and Physical Developer. Both of these reagents contain a silver salt, but they perform in a different manner. Silver Nitrate reacts to salt deposits in sweat while Physical Developer reacts to the presence of sebaceous secretions (oil).
Silver Nitrate is a light sensitive material so it is usually sprayed onto a document from an amber, light-tight bottle. If tray development is desired, available light must be shut off. Development under red darkroom lighting is the best method.
Allow the document to air-dry and then expose it to room light. Prints may become visible in several minutes, but development may be accelerated by briefly exposing the document to a
shortwave ultra violet light source.
Silver Nitrate developed latent print.
Physical Developer, while still using a silver compound, is not as light sensitive as Silver Nitrate. It produces a gray latent print, which is also somewhat fluorescent, so a normal longwave UV light may be used. The best method for Physical Developer processing is tray development.
When processing certain kinds of paper it is a good practice to neutralize them first with a short bath in Maleic Acid. This is especially important for bleached (typically any white) paper as these will turn completely brown-gray without the neutralizing step.
Physical Developer is packaged in two containers: the small bottle contains the dry reagents, which are emptied into the large bottle of liquid. Once mixed the shelf life is limited to a few days.
Tray-development is the most practical method of development. Latent prints, if present, will appear in a matter of minutes.
Either Silver Nitrate or Physical Developer is the final step since either process is destructive to subsequent testing with other reagents. Be certain to obtain the Material Safety Data Sheets (MSDS) covering the use of the reagents discussed in this article.
Physical Developer latent print.
For more information about the tools that real-world CSIs use every day, you may download a complete catalog covering all of the techniques discussed in this article series. Visit this WEBSITE and download just the individual sections that interest you. The catalog is FREE. Check out pages 90-92 to see photographs of latent prints developed with the materials used in these articles.
Don Penven is a freelance writer based in Raleigh, NC. He has over 30 years of direct and indirect experience in law enforcement and crime scene investigation.
The science of fingerprint identification, or dactylography, began nearly 4,000 years ago in the “Fertile Crescent,” the land between the Tigris and Euphrates Rivers in present day Iraq. King Hammurabi (1955-1913 BC) used finger seals on contracts and law officers of the day were authorized to secure fingerprints of arrested persons.
Little is known as to how the fingerprints were used. If actual point-to-point comparisons were made, people of that day surely had exceptional eyesight —since optical magnifiers weren’t invented until several millennia later.
In AD 650, nearly 600 years before Marco Polo visited “Cathay,” Chinese historian Kia Kung-Yen wrote of fingerprints used in an older method of preparing contracts. The law book of Yung-Hwui of the same period listed that the husband in a divorce decree had to sign the document with his fingerprint.
In AD 1100, Chinese novelist Shi-Naingan wrote in his book, The Story of the River Bank, “He compelled them to ink their fingers to record their fingerprints.”
In the late 1700’s, a German doctor, J.C.A. Mayer, reported that fingerprints are never duplicated by nature. A very astute observation — but Dr. Mayer left it at that.
Decades later, a student publishing his doctoral thesis in 1823 described fingerprint types and classified them into nine major groups. But author Johannes E. Purkinje gave them no identification value.
Most historians credit Sir William Herschal with being the first person to definitely use fingerprints for identification purposes. While working for the East India Company in Bengal, India, Herschal had natives place their palm prints on contracts and receipts. In 1858, when he began the practice, the idea was probably based on superstition; but Herschal quickly saw the value of fingerprints as a positive form of identification.
The first person given credit for using fingerprints to solve a crime is Henry Faulds. Faulds wrote in Nature magazine that when bloody finger marks or impressions on clay, glass, etc. exist, they may lead to the scientific identification of criminals. Faulds’ “chance impression” resolved a case of “…theft of rectified spirit.”
Up to this time, no unified system of physical identification existed beyond a general description of age, weight, marks, scars and so forth. Alphonse Bertillon, a French anthropologist, changed all that by introducing his system of “Anthropometry,” which consisted of exact measurements of various parts of the body (upper and lower arm, head, legs, etc.) A year later, in 1883, The Bertillon experiments were given permanent status and most countries in the Western world adopted the system.
In 1888, Sir Francis Galton, a noted British scientist, prepared a talk for the Royal Institute on Bertillon’s system, which kindled his interest in fingerprints. His research led to a meeting with Herschal and he built his knowledge from Herschal’s material. Galton went on to devise a classification system and he defined various points of identification in a fingerprint — known as “Galton Details,” or fingerprint minutiae.
Considerable progress was being made on this side of the Atlantic, too. Juan Vucetich set up Bertillon’s system for the LaPlatta, Argentina, police in 1891. This same year, he developed a classification system and began filing fingerprint records accordingly. The Vucetich System
is still in use in many Spanish-speaking countries.
Also in 1891 Sir Edward Richard Henry, Inspector General of Police in Bengal, India, experimented with Herschal’s fingerprint system. He then visited Galton and later developed his own classification system. A modified form of the Henry System is the basis for fingerprint classification and filing throughout much of the world today.
Henry eventually joined the Metropolitan Police (Scotland Yard) where he first set up the Bertillon system (in 1894), and later he initiated his fingerprint identification methods. In 1918 Henry was dismissed from the job following accusations of “oppression and injustice.”
More fingerprint work in South America led to the solution of a homicide using fingerprint evidence — the first such case in recorded history. Police Inspector Alvarez of LaPlatta, Argentina, solved the “Rojas Murder Case” with a bloody fingerprint found on a door. In 1896, anthropometry was abandoned in Argentina in favor of fingerprint identification.
The use of fingerprint identification in the United States was slow to develop. Most identification bureaus were locked into the Bertillon system until the now-famous Will West case at Leavenworth prison. When Will West arrived to serve his sentence in 1903, identification personnel insisted that he had been an inmate before. After being subjected to the Bertillon measurements, officials found the file of one William West, whose measurements were virtually identical to the person calling himself Will West. Even their photographs showed a remarkable resemblance.
But William West was still in prison serving a murder sentence. Their respective fingerprints were
taken, compared, and they bore no resemblance. This unique case established the value of fingerprint identification in this country.
It is interesting to note that later research indicates that Will and William West were most likely monozygote (identical) twins who were separated at a young age.
In 1904 the St. Louis, Missouri, Police Department was the first agency to set up a fingerprint bureau. Meanwhile, the International Association of Chiefs of Police (IACP) had established a central fingerprint file in Chicago. The complete file of some 810,000 records was turned over to the newly formed Identification Division of the F.B.I. Today the F.B.I. files contain several hundred
million record cards.
Advances in the state-of-the-art have led to computerization of fingerprint record files. Automated Fingerprint Identification Systems (A.F.I.S.) are in operation in many parts of the country. A.F.I.S. not only stores record cards in computer memory, it will match latent fingerprints from crime
scenes to its data bank. A well-known example of the speed of an A.F.I.S. at work was in California.
A latent fingerprint was entered into the system, and less than four minutes later the print was matched, and a killer who had eluded police for six years was identified and shortly apprehended.
Every human being carries with him from his cradle to his grave certain physical marks which do not change their character by which he can always be identified and that without shade of doubt or question these marks are his signature…and this autograph cannot be counterfeited, nor can he disguise it or hide it away. This ‘signature’ is each man’s very own — there is no duplicate of it
among the swarming populations of the globe. This autograph consists of the delicate lines or corrugations with which Nature marks the insides of the hands and the soles of the feet.
The interpretation of blood spatter was first mentioned in a paper written in the 1890s by a researcher at the Institute for Forensic Medicine in Poland, Dr. Eduard Piotrowski. His work, "Concerning the Origin, Shape, Direction and Distribution of the Bloodstains Following Head Wounds Caused by Blows." But it took nearly 50 years before cases that included the interpretation of blood spatters appeared.
A significant number of high profile criminal cases have been prosecuted when blood spatter evidence was included among the physical evidence. One such case was the highly publicized trial of the State of Ohio v. Samuel Sheppard. In 1955, Dr. Paul Kirk offered an affidavit on blood spatter analysis, which was the earliest instance for the legal system to be made aware of the value of blood spatter analysis. Kirk’s analysis was able to show the location of the victim and the assailant, and it showed that the victim was struck by the assailant’s left hand.
Other cases involving prominent personalities where blood spatter entered into the evidence were the O.J. Simpson murder case and the trial of noted author, Michael Peterson of Durham, NC.
A leading authority in this field is Dr.Herbert MacDonell, who published in 1971, "Flight Characteristics of Human Blood and Stain Patterns." MacDonell has trained countless crime scene investigators in blood spatter analysis as well as training analysts.
The blood spatter analyst is seeking the following information from blood stain patterns:
1. Is it blood? This can be determined by simple, portable field tests using chemicals such as Phenolphthalein or Leucomalachite. These tests are presumptive in nature and are not proof positive that the substance is blood. But the likelihood is that the substance is probably blood and not tomato juice or paint. But these tests do not differentiate between human and animal blood, which require further laboratory analysis.
2. Trajectory of the blood droplets: Using visual examination at first, the analyst can tell whether a droplet struck the surface at a 90-degree angle or at some more acute angle. When a blood droplet strikes the surface at 90-degress it leaves a circular stain. If it travels into the surface from angle, the stain will be elongated—resembling an exclamation point with the narrow end of the stain pointing in the direction of travel—away from the source.
3. Using specific measurements of the actual size of the stain (length vs. width), it can determine the actual angle of travel to the surface using a trigonometric formula.
4. Once the angle of incidence is determined, the analyst attaches strings to the surface that simulate the flight path of these droplets. The strings will all cross each other at some distance from the surface and this indicates the point of origin of the various stains.
Using this method, the analyst can determine if the victim was standing or kneeling and how far away he was from the surface that contained the blood stains. For photographs that illustrate the above steps, see the article posted HERE.
To become a blood spatter analyst, specific training is required to reach the point that the analyst is accepted as an expert in this field. Additional articles on blood evidence will be posted on this site shortly. To learn more about how CSIs identify possible blood stains at the crime scene, download a free technical bulletin at the website listed below.
The reconstruction of crime scenes is a miss nomenclature. You are in reality interpreting the information that you find by examining and processing the scene for evidence. This evidence will then permit you to make factual statements in regards to your findings. For instance, examining a footwear impression left at a scene you will be able to determine what direction the person was walking when that impression was made.
Therefore you are interpreting the information you discovered to develop a factual reconstruction. In other words you are placing your interpretations in a logical order to reconstruct what has taken place in the crime scene. This will apply to all crime scenes that are left intact and are not disturbed by the victims, paramedics or police officers.
Without this "virgin" crime scene the interpretation could be altered and may not be as it was when the suspect(s) were there. Never, never assume or guess at the reconstruction without all the facts from the interpretation.
As trained crime scene technicians you are expected to develop the maximum amount of information from the crime scenes. This information is developed by processing the scene for physical and testimonial evidence. The testimonial evidence is the interpretation of the facts in the crime scene.
Let’s take an armed robbery at a convenient store as an example. The store clerk is approached by an armed suspect who robs the store and flees from the store, jumps into an awaiting car and escapes from the scene. The store clerk gives the investigators a statement as to what has occurred. This statement will include what the store clerk observed.
Their observations will include the description of the suspect and vehicle. This is testimonial evidence. They will testify in court as to their observations, the same as a trained crime scene technician will testify to his interpretations. However his interpretations are based on facts that he will have to prove in court. This proof will be based on physical evidence and the interpretation of that evidence.
Let’s carry this a little farther. You are called to a residential burglary where unknown suspects forced their way into a residence and stole items belonging to the victim. You examined the residence and find that the back door has been forced open with the use of a wide pry type tool. You know this to be a fact because of the size and shape of the toolmark.
A closer examination of the toolmark reveals a blue paint transfer from the tool to the white wood door casing. Now you know for a fact that the tool used is a wide pry type tool that is either blue in color or has blue paint on it.
Since this is the point of entry to the residence you examine the outside area around it. You discover a footwear pattern in the soil leading to the point of entry. This same pattern is evident on the door where the suspects had also kicked the door to force it open.
Again you have factual evidence, the footwear pattern, to make this interpretation. You process this door and casing for fingerprints and discover cloth impressions. The cloth impressions would indicate that the suspects either had gloves on at this point or a cloth material over their hands.
Just because you find cloth impressions at the point of entry don't assume that the suspect kept his gloves on all the time. You may find an item that he had to handle with both hands and discover that he had a glove only on one hand.
Inside the residence you observe the same footwear pattern as found on the door and in the yard. This pattern leads to every room in the residence that has obvious disturbance caused by the suspects, i.e., drawers pulled out and dumped, closets rifled, jewelry boxes dumped on the bed, and so on.
This footwear evidence will lead you to interpret the direction that the suspect went inside the house. Finding different patterns of footwear impressions inside and out could tell you how many suspects were in the residence.
This procedure continues throughout the residence gathering physical evidence that will allow you to make factual interpretations of the crime scene. Unfortunately this information usually is not documented by the crime scene technician in his crime scene report. Documentation is made by notes, sketches and photographs. If you observe something in the crime scene then DOCUMENT IT!
How are you going to convince the judge or jury of your interpretations if you can't prove the facts as you observed them.
This is where most mistakes are made by the crime scene technician testifying in court hearings. They know what they saw but failed to properly document their observations.
There have been many cases "made" because of the documented interpretation of the scene by the crime scene technician. The following is an example of these cases.
CASE #1: Suspect in a business burglary denies any knowledge of the burglary. He then confesses to the investigators after he is told of the interpretation of the evidence found at the scene. The investigators told the suspect how he entered the business, that he was wearing cotton gloves with yellow fibers, what direction he went in the business, how he left and his footwear pattern was similar to what was found at the scene.
This was all based on factual evidence from the scene. The suspect confessed because he thought he was videotaped by a hidden camera at the crime scene. In his own words "No one would have known that (the interpretation) if you didn't have that hidden camera you would have never caught me."
CASE #2: The suspect in a brutal murder of his wife and child denied any knowledge of the crime. After being told of the interpretation of the blood spatter, how many times he struck the victims with the aluminum bat, and where he was standing at when he struck them, he confessed to the double murder.
CASE #3: Three brothers were home alone when according to the surviving brother one brother shot the other one and then shot himself. The scene was processed for evidence and the interpretation of the evidence indicated that the surviving brother was not telling the truth because the scene indicated that the shooting did not occur as was stated. After changing his story five times the surviving brother confessed to shooting both of his brothers just as the interpretation of the crime scene indicated.
You will be able to reconstruct the crime scene in court if you remember that the "reconstruction" is your interpretation of the factual evidence in the case. All facts or evidence in crime scenes are derived from the complete processing of the scene and the new "tools" we have to work with.
These new tools are: Blood spatter and flight interpretation, Electro-Static Dustprint Lifter, Super glue fuming, portable lasers, and alternate light sources. These are only a few of the modern day advances in equipment and techniques for processing crime scenes. However, even with "miracle" tools and techniques, if the evidence and facts of the case are not documented you will not be able to prove your interpretation of the scene.
Remember to never assume or guess and always document your observations by sufficient notes, photographs and sketches.
It is a great pleasure and a privilege that we are able to include in the Crime Scene Training Blog a series of articles created by MSgt. Hayden B. Baldwin (Ret.). Please take a moment to check out his bio at the link below
A crime scene investigator may be called to a crime scene 15 minutes before Thanksgiving dinner or just as the kids start to open their Christmas presents. It isn't unusual for the call to come after the crime scene technician is asleep in bed, sometimes after having worked a 12-hour day
But just because the crime scene investigator hasn't slept in 24 hours is no reason for missing an item of evidence or for under-working a crime scene. So it may be "just a burglary"? That burglary is just as important to the investigating agency as is any other case. The victim deserves the best investigative efforts possible, regardless of the type of crime under investigation.
The crime scene investigator dresses like the professional that he is: he could be mistaken for a salesman or for an executive on his way to the office. But this professional may be casting a tire track found in eight inches of snow or working in 95-degree temperature on a body found in the woods. He may have to crawl under a house to search for a spent cartridge.
The news media often give the attention to the investigating agency or detective when an arrest is made. When the case comes to trial, media attention often is focused again on the detective's testimony, or on the suspect. The crime scene investigator gives his testimony, then thinks about the fingerprint he lifted, the toolmark he cast, the cartridge case he located, and the various other types of evidence he processed that placed the suspect, beyond any doubt, at the scene of the crime. Successful case conclusion gives the crime scene investigator his job satisfaction.
The crime scene investigator may not be in the center of media coverage on a case, but his efforts do not go unrecognized. The investigators, the sheriff, the police chief, etc., continually express their appreciation. Since the successful conclusion of a case results from a combination of various specialties, this recognition by the crime scene investigator's peers is better than any news media coverage.
In the endeavor of completing a work task certain criteria to complete the work task is needed. Crime scene processing is no different in that respect than to other work related tasks such as exchanging a motor in a car, painting a landscape scene or preparing a meal. There are certain tasks related to each work objective. In the field of crime scene processing several books have been written on what these tasks are and how they should be incorporated into the field of crime scene processing. Yet each book varies only in the technique used, not in a change of the basic protocol used for the processing of crime scenes.
A few years ago I attended a lecture on "25 Ways to process a crime scene." It was probably the most boring lecture I've attended in years, but it did highlight one point that most of us have taken for granted. How do you explain to someone the mechanics of thoroughly processing a crime scene? It sounds simple, but in fact crime scene processing is a very intricate and interwoven multiple task function. It is difficult to explain to someone the exact protocol that will be used at every crime scene. Each crime scene is different and may require a different approach to processing the scene. However there is a basic crime scene protocol that should be adhered to in all crime scenes. These basic functions or tasks are as follows:
1. INTERVIEW 2. EXAMINE 3. PHOTOGRAPH 4. SKETCH 5. PROCESS
Interview is the first step in processing a crime scene. The crime scene technician must interview the first officer at the scene or the victim to ascertain the "theory" of the case. Basically what allegedly happened, what crime took place, and how was the crime committed. This information may not be factual information but it will give the crime scene technician a base from which to start.
Examine the crime scene as the second step in the protocol. Examine the scene for what? To ascertain if the "theory" of the case is substantiated by what the crime scene technician observes. Examining the scene to identify possible items of evidentiary nature, identify point of entry and point of exit, and getting the general layout of the crime scene.
Photograph the crime scene is the third step in the protocol. Photographing the crime scene to record a pictorial view of what the scene looks like and to record items of possible evidence. Crime scene photographs are generally taken in two categories, overall views and items of evidence.
Sketch the crime scene is the fourth step in the protocol. A rough sketch is completed by the crime scene technician to demonstrate the layout of the crime scene or to identify the exact position of the deceased victim or evidence within the crime scene. A crime scene sketch may not be completed on every case, however some form of sketching usually occurs in most cases, i.e., on a fingerprint lift card to identify exactly where the latent was recovered.
The last step in the protocol is to process the crime scene. Process the scene for what? The crime scene technician will process the crime scene for evidence, both physical and testimonial evidence. It is the crime scene technician’s responsibility to identify, evaluate and collect physical evidence from the crime scene for further analysis by a crime laboratory.
The above five steps in the protocol of crime scene processing is intermingled with each other step. If the "theory" of the case dictates that the intruder forcibly entered the residence through a window then the crime scene technician will need to examine the window area for footwear patterns, toolmarks, trace evidence and latent finger prints.
Upon finding such items of evidence the technician will need to photograph their location and possibly complete a sketch showing the exact location of the evidence or perhaps a sketch of the footwear pattern. This intermingling of the steps in the protocol will continue throughout the processing of the crime scene. Of course interwoven throughout these five steps is the recording of the crime scene by photographs, sketches, and field notes.
This protocol should be used in all crime scenes. Whether the crime scene is a recovered stolen vehicle or a multiple homicide where several crime scenes are involved the basic protocol is the same:
INTERVIEW, EXAMINE, PHOTOGRAPH, SKETCH and PROCESS.
The interpretation of blood spatter was first mentioned in a paper written in the 1890s by a researcher at the Institute for Forensic Medicine in Poland, Dr. Eduard Piotrowski. His work, "Concerning the Origin, Shape, Direction and Distribution of the Bloodstains Following Head Wounds Caused by Blows." But it took nearly 50 years before cases that included the interpretation of blood spatters appeared.
A significant number of high profile criminal cases have been prosecuted when blood spatter evidence was included among the physical evidence. One such case was the highly publicized trial of the State of Ohio v. Samuel Sheppard. In 1955, Dr. Paul Kirk offered an affidavit on blood spatter analysis, which was the earliest instance for the legal system to be made aware of the value of blood spatter analysis. Kirk’s analysis was able to show the location of the victim and the assailant, and it showed that the victim was struck by the assailant’s left hand.
Other cases involving prominent personalities where blood spatter entered into the evidence were the O.J. Simpson murder case and the trial of noted author, Michael Peterson of Durham, NC.
A leading authority in this field is Dr.Herbert MacDonell, who published in 1971, "Flight Characteristics of Human Blood and Stain Patterns." MacDonell has trained countless crime scene investigators in blood spatter analysis as well as training analysts.
The blood spatter analyst is seeking the following information from blood stain patterns.
1. Is it blood? This can be determined by simple, portable field tests using chemicals such as Phenolphthalein or Leucomalachite. These tests are presumptive in nature and are not proof positive that the substance is blood. But the likelihood is that the substance is probably blood and not tomato juice or paint. But these tests do not differentiate between human and animal blood, which require further laboratory analysis.
2. Trajectory of the blood droplets: Using visual examination at first, the analyst can tell whether a droplet struck the surface at a 90-degree angle or at some more acute angle. When a blood droplet strikes the surface at 90-degress it leaves a circular stain. If it travels into the surface from angle, the stain will be elongated—resembling an exclamation point with the narrow end of the stain pointing in the direction of travel—away from the source.
3. Using specific measurements of the actual size of the stain (length vs. width), it can determine the actual angle of travel to the surface using a trigonometric formula..
4. Once the angle of incidence is determined, the analyst attaches strings to the surface that simulate the flight path of these droplets. The strings will all cross each other at some distance from the surface and this indicates the point of origin of the various stains.
Using this method, the analyst can determine if the victim was standing or kneeling and how far away he was from the surface that contained the blood stains. For photographs that illustrate the above steps, see the article posted HERE.
To become a blood spatter analyst, specific training is required to reach the point that the analyst is accepted as an expert in this field. Additional articles on blood evidence will be posted on this site shortly. To learn more about how CSIs identify possible blood stains at the crime scene, download a free technical bulletin at the website listed below.
In Part 1 of this series we offered a description of what a latent print is, and an overview of latent print processing methods. This article will explain the various types of powders used to develop latent prints and their specific uses.
One of the first known methods for developing latent prints used black powder made from lamp black or soot (carbon black) and white talc. The powder clings to the moisture content of the latent print as described in Part 1. Dark powders are used on light-colored surfaces and light colored powders are used on dark surfaces in order to give visual and photographic contrast.
Listed below are the very basic powders that have been in use throughout the world for decades. Latent print powders are divided into the following five categories:
Author’s Note: All of the powders listed below are applied with a soft bristle brushes such as squirrel hair, goat hair, fiberglass, makeup style brushes, etc. More on this will be offered in a moment.
Oxide powders: This formulation is useble on many non-porous (STICK) surfaces such as most metals, painted wood, plastics and glass. Some examples are: Black, White, Red and Gray. These powders are not recommended for use on highly polished (SLIP) surfaces such as chrome, silver, etc. Oxide powders are known as “SLIP” powders, and are recommended for use on “STICK,” non-porous surfaces.
Special oxide formulations are necessary for specific “problem” surfaces like zinc-plated (galvanized) steel used to make vending machine coin boxes.
Metallic powders, as the name implies, are formulated using various metals like aluminum, brass and copper. Metallic powders are recommended for use on highly polished (SLIP) surfaces. Latent prints on chrome-plated metal or silver are generally destroyed (wiped away) if oxide powders are used. Metallic powders are referred to as STICK powders as they stick to latents on SLIP (slippery) surfaces, and they should not be used on STICK surfaces as the powder tends to stick to the entire surface and not just the ridge structures present..
Combination powders: Combinations are created by a specific formulation of oxide and metallic powders. An example is the very popular Silver/Black latent powder. This is a mixture of aluminum (metallic) and black (oxide) powders. The advantage is that combination powders may be used on virtually any non-porous surface. Another unique feature offered by this type of powder is that on dark surfaces the developed latent prints appear in a light color and on light surfaces the prints will be dark. If your budget is severely limited, and you require a versatile, extremely useful and effective powder, use a combination-formulated powder such as Silver/Black, Silver/ Gray or Silver/Red. This will eliminate having to carry several different oxide and metallic powder formulations.
·Fluorescent powders: This category of powders employ a base substance that is fluorescent in nature when exposed to ultra violet (black) light or alternate light sources like blue light. Fluorescent powders are considered to be oxide in their properties and are best used on non-polished surfaces. The particular advantage of a fluorescent powder is the fact that it may be used on multi-colored, patterened backgrounds. When the area under scrutiny is darkened, and an alternate light source is used, the fluorescent material emits a brilliant glow that reveals the fingerprint ridges, and the background all but disappears—making photography easier to accomplish.
Magnetic powders: Magnetic powders first appeared on the market during the early 1970s. Magnetic formulations include iron or iron oxide as the basic component. Various pigments are added to provide background contrast. White, black, silver and red are commonly available. Some manufacturers also offer combination formulas as well as fluorescent magnetic powders. The principle advantage of a magnetic powder is that it is applied by a magnetic applicator wand and not a brush. The wand is equipped with a strong magnet and when held about a ½-inch or so above the powder, the powder is drawn to the magnet and forms a powder brush. Thus—only the powder touches the surface being dusted, and this will eliminate any chance of damaging the fragile latent print on the surface. Magnetic powders are not recommended for use on surfaces containing iron or steel.
There are a several kinds of feather dusters available to be used in place of a brush. Many CSIs, prefer feather dusters when applying fluorescent powders. They are also a valuable tool in “cleaning up” or removing excess powder from latents developed using a brush
Application Procedures: As noted above, only magnetic powder is applied without a brush. The remaining powders require use of a soft bristle brush. Brushes employing fiberglass or carbon-fiber strands are thought to be the softest
Applying powder or dusting the surface is accomplished using these recommended steps
1. After deciding which formulation to use, measure out a small quantity of powder onto a clean sheet of paper. Do not dip the brush directly into the powder jar as this tends to compact the powder, and it will also add contamination from previously dusted surfaces into the powder
2. The best rule to follow when it comes to using powder is “Less Is Best.” Pickup the powder with the tip of the bristles, and lightly tap off any excess powder
3. Apply the powder to the surface in gentle sweeping strokes. Some CSIs use a back and forth, side to side motion—some users twirl the brush between the thumb and index finger. Practice applying powder to various surfaces before attempting to use these methods at an actual crime scene. Learn what works best for you
4. As developed latents appear, expand the search area by applying more powder. Remember, you are processing areas that probably have been touched.
5. After prints are developed they must be photographed before any attempt is made to “lift” them
Be certain to include a scale (ruler) in each photo. This is a necessity especially if digital cameras are used at the scene. If the latents recovered are to be submitted to an online search such as the Automated Fingerprint Identification System (AFIS), the entries must be 1:1 in size. A scaled photo makes this possible
After photos are taken, the developed latents may be lifted from the surface. Numerous methods are available for this purpose. Included in this arsenal of lifting methods are: latent print lifting tapes (available in 1-inch to 4-inch widths, Hinge Lifters, EZ-Lifters and Rubber/Gel Lifters. And don’t forget that you will need backing cards when making lifts with lifting tapes.An exact description of the lifting process is discussed at the website listed below
So there you have it. But I’ll close this article with a few warnings:
Be certain to obtain a Material Safety Data Sheet (MSDS) from the powder manufacturer. Some powders contain hazardous substances that you must be made aware of. The MSDS will explain what safety precautions you should take to protect yourself such as wearing a dust respirator, eye protection, latex gloves and a disposable jumpsuit or lab apron
Another precaution is to consider the mess you may leave behind. Most latent powder manufacturers get frequent phone calls from irate home and business owners who find it next to impossible to clean up the powder left behind. Black latent powders are especially difficult, if not impossible, to remove from carpets, furniture and other materials.
The following link will take you to a website where you can learn a great deal more about latent print development: Download this training free guide: “Overview of Latent Print Development.” You may also download individual Catalog Sections.
Don Penven is a freelance writer based in Raleigh, NC. He has over 30 years of direct and indirect experience in law enforcement and crime scene investigation.
1. A latent fingerprint is one that is generally not visible unless it is treated in some manner. The print itself is composed of moisture—mostly water—but it also contains small amounts of the constituents of perspiration (sweat), like amino acids, choline, sodium and potassium salts and urea.
2. The palms of the hands and soles of the feet are covered with friction ridges, and these ridges have sweat pores along their surface. These two areas have one single type of sweat gland: Eccrine glands. Only water and the substances listed above are exuded from these glands.
3. Other parts of the body have two other types of sweat glands: Sebaceous and Apocrine glands. Sebaceous glands exude fatty acids, glycerides and hydrocarbons. In other words these secretions are oily in nature. The Apocrine glands secret water along with ions of sodium, potassium and iron as well as proteins, ammonia, carbohydrates and cholesterol. Sebaceous glands are associated with hair follicles.
4. When the hands come into contact with the face, arms and other parts of the body they become contaminated with this sebaceous, oily mix.
Over the years several methods for “developing” latent prints have evolved. The most often used development methods currently are fingerprint powders, chemical processing and fuming techniques. Each of these methods will be examined in more detail in subsequent articles.
You might say that locating areas that may yield latent prints requires an intuitive approach as well as some common sense. Prior to any attempts being made to recover latents the crime scene investigator (CSI) performs a walk-through of the scene, making notes of potential spots where latents may exist.
The CSI would first determine the “probable” point of entry. This would include doorways and windows, even a hole cut through the roof. Next he tries to envision the path that the perpetrator took through the scene. The very nature of the crime will assist in determining the best spots to begin the latent processing steps: A burglary will most likely mean that the subject touched or moved certain objects, opened drawers or cabinet doors. etc.; while a homicide or sexual assault would have involved very different activities.
Depending on the number and training levels of those working the crime scene, the team leader will make specific assignments. The first priority is securing the scene. This begins with establishing the exact boundaries of what constitutes the scene, and tehn setting up barrier tapes and/or posting personnel who monitor or restrict access to the areas designated as being part of the scene.
The crime scene must be fully documented prior to any type of evidence collection. Thus, the overall scene is photographed and when possible—videotaped. A rough crime scene sketch is then begun. Documentation must also include establishing a chain of custody for the evidence collected. (See related article on Crime Scene Protocol.)
This all involves time. Unlike certain TV shows, performing a complete crime scene investigation and arresting the perpetrator takes a lot longer than the hour of storyline and commercials.
Forthcoming articles will give specific information of the three principal methods of Latent Print Development mentioned above.
If you would like to learn more about latent fingerprint development techniques, you may download a free technical bulletin. Click here for access to your copy. Overview of Latent Print Development Techniques.
You may also download a complete catalog of crime scene equipment , or just the specific sections that interest you. Click HERE for access.
Don Penven is a freelance writer and photographer based in Raleigh, NC. He has over 30 years direct and indirect experience in law enforcement and crime scene investigation.
The wildly popular TV show, “CSI-Crime Scene Investigation” has changed the public’s view on how crimes are investigated and solved. In a sense this show has accomplished two points:
1. It has given the public first hand information about the tools and procedures that crime scene investigators use to solve crimes.
2. It has given the public unrealistic expectations in believing all law enforcement agencies should be able to catch the criminal in just 42-44 minutes.
Budget constraints often hamper investigative agencies in procuring the latest tools needed for effective crime scene investigation. Budgets also restrict training opportunities for officers too. Yet the locating, collecting, preserving and evaluating physical evidence from crime scenes is what helps to get convictions and /or exonerate a falsely accused suspect..
Latent fingerprints remain one of the most valuable kinds of physical evidence, and although DNA evidence is becoming increasingly valuable, latent prints have an excellent track record.
Latent fingerprints are the result of physical contact with a surface by the fingers or palms of the hands. Both the palms and soles of human feet are covered with “friction ridges,” and these ridges are dotted with sweat pores. These pores are part the body’s waste disposal system and they secrete mostly water that is populated with a variety of waste products like amino acids, urea, sugar, creatinine and choline.
But the fingertips are often contaminated by oily secretions from contact with other parts of the body that harbor sebaceous glands. The face, ears and upper body are covered with pores that secrete oily sebaceous content, which includes fatty acids, glycerides and hydrocarbons.
Several methods are available to CSIs for use at the crime scene. Below are tools and materials used to locate and develop latent fingerprints:
1. Latent print development powders: Latent powders include a variety of formulations. The first consideration facing the evidence collection team is the type of surface to be processed. Nonporous surfaces like metal, painted wood, glass and most plastics generally require the use latent print powders. But specialized powders have been developed that improve chances of getting useable latent prints on a variety of surface textures. Background color is also a consideration. A light colored powder is used on dark surfaces and dark powders are used on light surfaces to ensure good photographic contrast. Latent powders are applied to surfaces using soft bristle brushes.
Highly polished surfaces like chrome-plating and silver objects require the use of powders formulated from metal—like aluminum, copper and brass particles. Other non-porous surfaces are processed with “Oxide” formulated powders like black, white, gray, and red.
2. Porous surfaces such as paper, cardboard and raw wood are best treated with chemicals like DFO, Ninhydrin, Silver Nitrate or Physical Developer. These chemicals are used in liquid form and are either sprayed onto the evidence or development in a tray is used.
3. Chemical fuming is the third choice for latent print development. There are two popular fuming processes: Iodine fuming and Cyanoacrylate (Superglue) fuming. Iodine fuming works best on porous surfaces (paper, cardboard and raw wood). Iodine crystals undergo a transformation when low heat is applied to them. This causes the Iodine to sublimate, which is when a solid like the crystals transforms in to a gas (fumes). Iodine fuming is practiced in an enclosed area of some sort. At the crime scene a zip-top plastic bag may be used as a “fuming chamber.” Iodine fumes react with the oily contents of latent print residue and an orange-brown color appears that conforms to the ridge structure of the print.
Cyanoacrylate or superglue fuming is used on nonporous surfaces like metal, painted wood, glass and plastic. Again a sealed chamber is needed for development. Superglue forms a very persistent bond with many surfaces, but it does not work unless moisture is present on the surfaces to be bonded.
Normal humidity can fulfill the moisture requirement. A small amount of superglue is paced inside the chamber with the evidence undergoing evaluation. It could take typically two to three hours for the fumes to “polymerize,” or to cover and harden on the moisture content of a latent print.
Development may be accelerated by the addition of heat (like a small coffee warmer) or by applying the glue to a cotton pad. The cellulose content of cotton causes considerable heat to develop.
In review, latent powders, chemicals and fuming techniques fill the crime-solving toolkit of the CSI. To get more information on any of these processes you may download a FREE Training Manual that includes a great deal of instructional material. “Overview of Latent Print Development Techniques.”
To sign up for e-mail alerts when new content is added please CLICK HERE!
You may also download specific sections of the catalog if desired. Click HERE!.
The reconstruction of crime scenes is a miss-nomenclature. You are in reality interpreting the information that you find by examining and processing the scene for evidence. This evidence will then permit you to make factual statements in regards to your findings. For instance, examining a footwear impression left at a scene you will be able to determine what direction the person was walking when that impression was made.
Therefore you are interpreting the information you discovered to develop a factual reconstruction. In other words you are placing your interpretations in a logical order to reconstruct what has taken place in the crime scene. This will apply to all crime scenes that are left intact and are not disturbed by the victims, paramedics or police officers.
Without this "virgin" crime scene the interpretation could be altered and may not be as it was when the suspect(s) were there. Never, never assume or guess at the reconstruction without all the facts from the interpretation.
As trained crime scene technicians you are expected to develop the maximum amount of information from the crime scenes. This information is developed by processing the scene for physical and testimonial evidence. The testimonial evidence is the interpretation of the facts in the crime scene.
Let’s take an armed robbery at a convenient store as an example. The store clerk is approached by an armed suspect who robs the store and flees from the store, jumps into an awaiting car and escapes from the scene. The store clerk gives the investigators a statement as to what has occurred. This statement will include what the store clerk observed.
Their observations will include the description of the suspect and vehicle. This is testimonial evidence. They will testify in court as to their observations, the same as a trained crime scene technician will testify to his interpretations. However, his interpretations are based on facts that he will have to prove in court. This proof will be based on physical evidence and the interpretation of that evidence.
Let’s carry this a little farther. You are called to a residential burglary where unknown suspects forced their way into a residence and stole items belonging to the victim. You examined the residence and find that the back door has been forced open with the use of a wide pry type tool. You know this to be a fact because of the size and shape of the toolmark.
A closer examination of the toolmark reveals a blue paint transfer from the tool to the white wood door casing. Now you know for a fact that the tool used is a wide pry type tool that is either blue in color or has blue paint on it.
Since this is the point of entry to the residence you examine the outside area around it. You discover a footwear pattern in the soil leading to the point of entry. This same pattern is evident on the door where the suspects had also kicked the door to force it open.
Again you have factual evidence, the footwear pattern, to make this interpretation. You process this door and casing for fingerprints and discover cloth impressions. The cloth impressions would indicate that the suspects either had gloves on at this point or a cloth material over their hands.
Just because you find cloth impressions at the point of entry don't assume that the suspect kept his gloves on all the time. You may find an item that he had to handle with both hands and discover that he had a glove only on one hand.
Inside the residence you observe the same footwear pattern as found on the door and in the yard. This pattern leads to every room in the residence that has obvious disturbance caused by the suspects, i.e., drawers pulled out and dumped, closets rifled, jewelry boxes dumped on the bed, and so on.
This footwear evidence will lead you to interpret the direction that the suspect went inside the house. Finding different patterns of footwear impressions inside and out could tell you how many suspects were in the residence.
This procedure continues throughout the residence gathering physical evidence that will allow you to make factual interpretations of the crime scene. Unfortunately this information usually is not documented by the crime scene technician in his crime scene report. Documentation is made by notes, sketches and photographs.
If you observe something in the crime scene then DOCUMENT IT!
How are you going to convince the judge or jury of your interpretations if you can't prove the facts as you observed them.
This is where most mistakes are made by the crime scene technician testifying in court hearings. They know what they saw but failed to properly document their observations.
There have been many cases "made" because of the documented interpretation of the scene by the crime scene technician. The following is an example of these cases.
CASE #1: Suspect in a business burglary denies any knowledge of the burglary. He then confesses to the investigators after he is told of the interpretation of the evidence found at the scene. The investigators told the suspect how he entered the business, that he was wearing cotton gloves with yellow fibers, what direction he went in the business, how he left and his footwear pattern was similar to what was found at the scene.
This was all based on factual evidence from the scene. The suspect confessed because he thought he was videotaped by a hidden camera at the crime scene. In his own words "No one would have known that (the interpretation) if you didn't have that hidden camera you would have never caught me."
CASE #2: The suspect in a brutal murder of his wife and child denied any knowledge of the crime. After being told of the interpretation of the blood spatter, how many times he struck the victims with the aluminum bat, and where he was standing at when he struck them, he confessed to the double murder.
CASE #3: Three brothers were home alone when according to the surviving brother one brother shot the other one and then shot himself. The scene was processed for evidence and the interpretation of the evidence indicated that the surviving brother was not telling the truth because the scene indicated that the shooting did not occur as was stated. After changing his story five times the surviving brother confessed to shooting both of his brothers just as the interpretation of the crime scene indicated.
You will be able to reconstruct the crime scene in court if you remember that the "reconstruction" is your interpretation of the factual evidence in the case. All facts or evidence in crime scenes are derived from the complete processing of the scene and the new "tools" we have to work with.
These new tools are: Blood spatter and flight interpretation, Electro-Static Dustprint Lifter, Super glue fuming, portable lasers, and alternate light sources. These are only a few of the modern day advances in equipment and techniques for processing crime scenes. However, even with "miracle" tools and techniques, if the evidence and facts of the case are not documented you will not be able to prove your interpretation of the scene.
Remember to never assume or guess and always document your observations by sufficient notes, photographs and sketches.
Special Note: During courtroom testimony in a very high profile homicide in North Carolina, the head CSI testified that he doesn’t take notes at the crime scene. We merely writes-up his report when he returns to headquarters. This really challenges the credibility of the witness. MSgt. Baldwin stresses the need for full DOCUMENTATION. Those little spiral-bound notes books are actually very cheap! –Don Penven
Dr. Tom Harper thought he had committed the perfect crime. He had shot his wife in a manner that should have left the bullet hard to find and identify. Then he had repeatedly stabbed her dead body with a kitchen knife, and after wiping off any fingerprints, dropped the knife in their backyard. Nearby, he made several impressions in the soft dirt with a sneaker that was two sizes larger than his shoe size. The house had been ransacked, and jewelry and some other item were missing. It looked like the perfect setting for a random house invasion scenario.
Establishing an Alibi
Dr. Harper, the director of a large dental clinic, then left his house through the back woods and picked up his car, which was on an isolated road about a half mile away. One of the advantages of living way out in the country was in having no neighbors close by to see things they shouldn't. Harper proceeded to his office and went into a 9:00 am meeting with his staff. While he was committing this crime, he periodically went to his laptop and typed an e-mail to several people to establish that he was in his office all the time. To bolster his alibi, he sent the e-mails to his office computer using remote desktop software, and then forwarded them to the recipients. There would be no trace of the e-mails coming from his house.
Alice Harper was a large woman who worked out regularly at the gym. Tom Harper knew that he would never be able to stab her without her fighting back and leaving signs of a struggle. His plan was to shoot her in the back at close range with a small caliber .22 pistol. His knowledge of anatomy allowed him to shoot her in a way that would penetrate the abdominal aorta and cause her to immediately bleed out into her abdomen. Once on the floor, he would stab her repeatedly with a kitchen knife. Hopefully, at autopsy, they would only look at the stab wounds and not look for a small gunshot wound in her back. To ensure this, he also stabbed her in the back several times, including through the gunshot wound area.
The Problem
But this plan left a problem: the bullet. Surely the medical examiner would find the lead slug. He had looked into frangible .22 bullets, something like a CCI Quik-Shok, but they only fragmented into two or three pieces and the likelihood of one or more being found would be too great. This kind of bullet would also tear up some other organs, and he wanted this to be a clean shot into the aorta. When he stabbed her, he would be sure to hit the aorta first in the front, making it look like a knife wounds had ruptured it.
This problem plagued him until one day, as he was rebuilding a patient's broken tooth, he had a thought. What if he removed the bullet from the .22 shell and built up a bullet made of dental restorative composite, like Gradia or some other polymer material? If he made the material not too smooth on the surface, it would probably be overlooked as a bone fragment, and he could color the composite to match bone. On studying some literature, he found that by incorporating calcium phosphate gel into the composite when he made it, the bullet would be strong enough to penetrate the body, but then break into several pieces. Furthermore, if he stabbed her in the stomach, the hydrochloric stomach acid would leak out, and could dissolve the calcium gel, degrading the bullet fragment even further.
The Crime
Harper was convinced his scheme was foolproof. He prepared several bullets, then shot them into watermelons out in the woods, adjusting the polymers till he got the effect he wanted. He picked a Thursday morning to shoot her, knowing that her best friend would come at around 10:30 am to pick her up to go shopping. His last task was to break the window in the back door at the kitchen, the point of entry for the robber.
When her best friend called 911 reporting her dead, the local crime scene investigators and coroner soon arrived at the Harper residence. The coroner did a preliminary exam at the scene, and determined that the first knife wound had apparently penetrated the aorta. This would explain the lack of significant bleeding at the site of the other knife wounds.
Severing of the aorta caused her to bleed into the abdominal cavity so fast that her blood pressure fell, and blood was not readily supplied to the other wound areas. Tom, who was sitting nearby appearing to grieve over his wife's death, heard the coroner tell the investigators this. He mused to himself that they had bought it, so far.
The CSI team finished their work hours later, but found little physical or trace evidence to go on. The murder weapon was found on the lawn, but wiped clean of prints. They sent it to the lab to be superglue-fumed for latent prints. Cast of the large shoe prints in the soft dirt were made, and a variety of fibers and hairs were bagged, but they all would turn out to be either those of Alice, Tom, or their son Alec, who was away at college.
A Lingering Suspicion
Still, to investigators it looked a little too clean--a little too perfect. Knowing that the husband is always a potential suspect in homicides, Harper cooperated with the police in all interrogations. A co-worker who was interviewed mentioned that Harper had worn a red flannel shirt the day of the murder. On a hunch, the lead CSI asked Tom for the clothes he was wearing that day. Since Harper was right handed and also wore his watch on his right hand, the watch was also collected. Harper did not see any problem with giving them these items; after all, he wasn't there at the time of the crime.
Newton Gets His Man
Dr. Harper, a distinguished dentist in the community, forgot a basic principle of physics: to every action there is an equal and opposite reaction. Yes, Newton's Third Law of Motion was about to spoil the good doctor's plan. Analysis of the red shirt at the crime lab revealed a radiating pattern of small mist-like blood droplets within the red fabric of the shirt. The victim was shot with a small caliber .22, which would only produce blood spatter for a distance of two or three feet. To get his shot positioned right to hit the aorta, Harper had walked up to within a foot of his wife before he pulled the trigger. Similar analysis of the watchband with Luminol and an ultraviolet alternative light source showed bloodstain on the band. A sample of this blood submitted for DNA analysis established that the blood was that of Alice Harper.
Further Evidence
To solidify the case, they also found gunshot residue (GSR) on the shirt. The potential residue particles were lifted from the fabric with double sided tape, and then subjected to scanning electron microscope analysis. Now the victim's clothing and back were tested for GSR. GSR on Harper's shirt matched GSR removed from Alice Harper. One again, Newton's Third Law came into play in solving this crime.
The doctor's plan to commit the perfect crime was spoiled by a principle he learned in a high school physics class. But more important is that good forensic analysis provided the evidence necessary for another successful conviction.
Doug Hanson, Ph.D.is a Ph.D. Biochemist who has operated toxicology and analytical chemistry laboratories for over 25 years. He is also a freelance writer who has written extensively for law enforcement, EMS and first responder magazines. His areas of expertise and written articles include: forensic investigation, DNA analysis, blood spatter, trace analysis, toxicology, drug and analytical chemistry, and forensic anthropology among others. He has written about car bombs, IEDs, soft targets, biological and chemical agents and attack scenarios. He has written on juvenile arson and illegal meth labs. Doug has written and published a book entitled The Eider Files, a novel about bioterrorism.
Thank you for visiting us. The intent of this blog is to provide the most comprehensive, up-to-date training in crime scene investigation available on the Internet today. Present plans include our making at least one post per week. Once we are up and running, and the interest is there, we will add additional posts with greater frequency.
After a thorough search for information on actual crime scene training sites we found that they are few and far between. Most of what is available are in Website formats, so it isn't practical for those viewing these training sessions to offer any interaction with us. A blog makes that possible, so we encourage our readers to post comments--pro or con--about what you find on these pages.
And of course, we are open to your suggestions, tips and ideas too.
As time goes on, we will cover a great many topics such as: latent print development (powders and chemicals); collection of micro-particle evidence; physiological fluid identification and collection; blood spatter analysis; gunpowder particle identification and collection; impression evidence collection (two and three-dimensional impressions); narcotics and dangerous drugs identification and collection; serial number restoration; proper handling and collection of electronic devices like cell phones, computers, pagers, iPods, iPads, etc. and a great deal more.
The CSI Effect has warped the image of the public at large with incredible crime solving techniques. When TV show producers have a huge budget to gain viewers, it hurts those agencies who do not have the funds and resources to solve a murder in 48 minutes. The down and dirty facts are that solving a crime involves many hours of evidence locating, recording and collection. It's a tough job--but someone has to do it.
Crime scene investigation involves more than high tech gadgets, it involves a large measure of common sense. We can teach you the basics--what to look for, how to collect it and how to evaluate it. But there is a certain intuitive sense that goes along with the task. If you have it, you will be a hero among your peers. If you don't--then you'll have to develop it. We hope that we can help you with that--to give you--the CSI, the motivation and the competence to do the job and to do it successfully.
Crime scene investigation is largely a matter of observation. The CSI must put himself into the body of the long-gone perpetrator. How did he get in? What course did he follow through the scene? And even what was he thinking?
Criminals have a blind-sided motivation: 1. They think they can get away with it. 2. They don't believe they will get caught.
You, the CSI, have to prove them wrong on both counts...and you will do it with something called physical evidence. "Book 'em Dano!"
The public view of criminal investigators has evolved over the years. Law & Order was a very popular TV show for years and it's still running--with several offspring. Lennie Briscoe was a legend. How many times did he enter a crime scene and take a pencil and shove it down the barrel of a murder weapon to pick it up? God rest his soul. Lennie is gone but a new cadre of detectives have taken his place.
The point is that we have to re-educate the public so they will not expect miracles from law enforcement in particular--and specifically the CSI.
PHYSICAL EVIDENCE...
Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more, bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value.
—Paul L. Kirk. 1953. Crime investigation: physical evidence and the police laboratory. Interscience Publishers, Inc.: New York.
More mistakes are made in crime scene investigation than any other part of police work." The person who wrote that is long gone but the sentiment is still true today.
Please note: The first lesson to be posted is An Introduction to Latent Fingerprints. Check the Latent Print page. You are encouraged to download a free training manual: "Overview of Latent Development Techniques"
