Crime Scene Training

How Police Find Latent Fingerprints—Part 4—Iodine and Superglue Fuming

By: Don Penven, Technical Support group

Review from Part 1 of this series:

The three contemporary methods used to develop latent fingerprints are:

• Latent print powders: oxide, metallic, combination, fluorescent and magnetic powders
• Chemical development: DFO, Ninhydrin, Silver Nitrate or Physical Developer
• Fuming: Iodine and Superglue fuming

 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, lactic acids, creatinine, choline, sugars and uric acid.

 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. Sweat from these two areas has one single kind of sweat glands: Eccrine glands. Only water and the substances listed above are exuded from these glands.

                                                                                                           Portable Fuming Chamber

 3. Other parts of the body have two other sweat glands: Sebaceous and Apocrine glands.  Sebaceous glands exude fatty acids, glycerides and hydrocarbons. In other words these secretions are oily in nature. Sebaceous glands are associated with hair follicles. The Apocrine glands secret water along with ions of sodium, potassium, and iron as well as proteins, carbohydrates and cholesterol.

 4. When the hands come into contact with the face and hair they become contaminated with this mix.

 Iodine Fuming: Iodine crystals have a unique characteristic—when exposed to air above room temperature they begin a process known to scientists as sublimation. This process is when a solid like iodine crystals converts directly into a gas—iodine fumes. All it takes is a little heat to accelerate the sublimation process.

 Iodine fuming is a process used to develop latent fingerprints on porous surfaces such as paper, cardboard and raw wood. Criminalists and crime scene investigators have found this to be a valuable tool for developing latent prints at the crime scene or the crime lab. But iodine fuming has a few shortcomings.

 The iodine method of latent print development is generally the first step in the attempts to develop latent prints that are thought to be reasonably fresh. The advantage of this method is that it is non-destructive to subsequent testing using other chemicals.

 Iodine fuming requires no sophisticated apparatus in order to deliver its fumes onto a porous surface. Iodine fumes react to the sebaceous sweat secretions (oil) that contaminate the fingertips. Touch your nose, cheek, ears, arms and chest and you have these secretions on your fingers.

 The iodine fumes develop latent prints that are orange to brown in color. This process works best on prints that are known to be fresh; like a ransom note, a holdup note handed to a bank teller or even a suicide note.

 But as mentioned, iodine fuming has its shortcomings—mainly that the prints that do appear are fugitive—they begin to fade shortly after development; and iodine fuming only works on prints that are thought to be reasonably fresh. You will hear more on this in a moment.

The fuming procedure is relatively simple:

 1. Iodine crystals are placed in a confined area along with a document or other porous items. At the crime scene this can be a zip-top plastic bag. In the crime lab it can be a converted fish tank, or a fuming chamber specifically built for this purpose.

2. A low level heat source is used to begin the sublimation process. This can be simply your hand wrapped around the zip-top plastic bag containing iodine crystals or an inexpensive coffee warmer.

3. The iodine fumes are usually visible—a kind of purple haze. Once the fumes are seen, the heat source may be removed. Prints will be visible in seconds.

4. The next step is to remove the evidence being processed, and then photograph any visible latent prints. Be certain to include a scale that is visible in each shot. If the prints are reasonably fresh, they should remain visible for 15-20 minutes or longer.

5. Once photographs are completed, you may apply an iodine enhancer/fixative to the developed prints, which provides a permanent image.

 Cyanoacrylate Fuming:

Back in the late 1970s members of the US Army Crime Laboratory in Japan were shown an interesting method for developing latent fingerprints on non-porous surfaces such as metal, painted wood, plastic and glass. Instead of using powders, members of the Japanese National Police Force used a material called cyanoacrylate to develop latent prints on most nonporous surfaces.

 At that period of time this material was popularly known as Super Glue. The name Super Glue was once trademarked, but through common usage, the term superglue has become generic and several cyanoacrylate manufacturers use it to describe their product.

 If you have ever used it, you know that cyanoacrylate has a very strong, noxious odor. You may have seen commercials long ago showing how a drop of this glue could bond an automobile to the hook on a crane, which lifted it off the ground. In any case, the glue does form a tight bond—provided there is a very thin film of moisture (water) on both surfaces to be bonded. And of course most surfaces on this planet have moisture on them as a result of humidity.

 So how can this develop latent prints? It is really very simple. A process known as chemical “fuming” is used. The crime lab technicians will carefully place several items of evidence into an enclosure. Early fuming tanks were nothing more than fish tanks with a cover of some sort.

Several drops of glue are measured out into a fuming tray (usually an aluminum cup-like object). This is placed in the chamber and the chamber is sealed up. Development without any sort of acceleration takes several hours, but a small coffee warmer can be used under the glue to accelerate the process.

 It is also possible to accelerate the fuming process by adding a few drops of the glue onto a cotton pad. To protect the surface of the floor in the fuming chamber, place the cotton pad on a piece of aluminum foil or one of the cups mentioned above. This is one very good reason for NOT wearing cotton gloves. Considerable heat is generated during the fuming process and may cause burns to the hands.

The glue fumes will circulate inside the chamber and will come in contact with the various items of evidence. The fumes will polymerize (turn into a solid) on any moisture on the objects—like fingerprint residue!

 The resulting developed latent prints will be hard as a rock, and will conform to the ridge structure that the suspect left behind. The developed prints are white in color so visual and photographic contrast may be added on light colored surfaces using fingerprint powders or dye stains.

 Many crime labs suggest that CSIs fume evidence with cyanoacrylate to prevent damage or loss of the latents during transport to the lab.

 If you would like to learn more about crime scene investigative techniques, an abundance of information is available from this website.

 You may download a free training manual, Overview of Latent Development Techniques

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References:

Lee Lofland, The Grave yard Shift-“”Ninhydrin and Iodine Fuming;” http://www.leelofland.com/wordpress/?p=259, April 11, 2011

 German, Edward, CLPE, FFS, Cyanoacrylate (Superglue) Fuming Tips, <www.onin.com>: April 11, 2011

 

 

Investigation of The Violent Crime (Part 2.)

INVESTIGATION OF THE VIOLENT CRIME (Part 2.)

Dr. Thomas O’Connor

Program Manager of Criminal Justice and Homeland Security

Director, Institute for Global Security Studies
Austin Peay State University
601 College Street
Clarksville, TN 37044 

http://www.drtomoconnor.com/3220/3220lect03.htm

 

Continued from Part 1.

ESTABLISHING THE VICTIM'S ROUTINE

    Next, you need to find out everything you can about your victim's background, especially their last activities in the previous 24 hours. This is called Applied Victimology, and it's your primary means of determining suspects. Examine telephone records, mail, email, food in refrigerator, business appointments, work and entertainment habits. Discretely inquire into romantic affairs.

    Look into what enemies the victim had (business-financial; political; religious; love life; entertainment world). Find out if your victim has a prior criminal record. Obtain a list of previously known addresses. If you can, find out about your victim's medical and mental history. You will need to assess whether this is the kind of victim that could engage in provocation or not, just as you've already established whether or not the victim put up a struggle.

WORKING WITH WITNESSES & BYSTANDERS

    Canvass the area and interview all cooperative, suspicious-looking, and even random, disinterested bystanders.  Don't make any "off the record" comments to reporters, and certainly don't tell anybody anything about any evidence you may or may not have found. Use your interview and interrogation skills. Get specifics about time and place from people so you can compare these specifics with the story they tell you later.

ESTABLISH THE MOTIVE

    At this stage, you're developing a viable theory about what happened. From your analysis of the crime scene and victim's background, you should be able to come up with at least 2-3 theories about what happened. Some standard motives are: anger, love, revenge, jealousy, and profit. More perplexing are hate crimes and senseless acts of violence. It may even be possible that you've got a serial killing on your hands.

    Many investigators wait until they've gotten a feel for the geographical and cultural aspects of the area the victim (and possible suspects) are from before taking a stab at motive.  This is the legwork of investigation; not so much putting people under surveillance, but checking out different parts of town, getting to know the habits and character of the people from that neighborhood, and linking this particular crime up with the patterns and motives from similar cases in similar neighborhoods. That, in short, is homicide investigation.

SEXUAL HOMICIDE, RAPE, AND CHILD ABUSE INVESTIGATION

    All victims of sexual assault, whether living or dead, should be examined in the same manner as for live victims of rape.  The optimal procedure is to have a sexual assault examiner (SART or SANE teams) conduct their business in conjunction with any criminal investigation and/or autopsy.  SART stands for Sexual Assault Response Teams (consisting of first responders, special investigators, and victim advocates), and SANE stands for Sexual Assault Nurse Examiner.  According to Gonzalez v. State of Texas 1991, SANEs are allowed to testify as expert witnesses.  

    The physical evidence that is most useful in a sexual assault case involves DNA, fingerprints, semen, hairs, fibers, and blood.  Other evidence may be useful (such as footwear impressions or fingernail scrapings), but these are the standard trace items focused on in every so-called "rape kit", and by the way, rape victims are not called "victims" but patients (the medical community prefers this term).  The logical solution to a rape case involves matching trace evidence from three places: the crime scene, the victim, and the perpetrator.  Alcohol and drugs are involved in about 33% and 25% of rape cases, respectively.    

    Most forcible rapists are stupid, predictable criminals.  99% of the time, they will attempt an alibi defense by claiming mistaken identity.  They will frequently say the rapist must be someone who looks like them.  Hence, the importance of physical evidence, like DNA, that individualizes the offender should be obvious.  A voice lineup may also be useful.  Once the evidence identifies them, they often change their story, and claim it was consensual sex after all.  "Oh yeah, I guess I was dating that girl", they will say, and those fingerprints of theirs must have been from one of their many sexual liaisons.  Depending upon how effective their lawyer is, courts normally have little tolerance for these kinds of games, but it's played 100,000 times a year, year in and year out in America, and police only have about a 50% clearance rate for rape.  Sex crimes that do not qualify as rape are called sexual assaults and occur 430,000 times a year.  Criminal investigators should therefore understand the importance of things like lie detectors and recorded or sworn statements or depositions in these kinds of investigations.  

    Another type of rapist is more insidious and uses newer drugs to erase the memories of victims (LeBeau & Mozayani 2001). The victim, out at a social event, meets and mingles with a respectable-looking person, who secretly slips gamma-hydroxybutyric (GHB), rohypnol, or ecstasy into the victim's drink. The victim, totally unaware, becomes incapacitated and is taken by the perpetrator to an apartment where she is raped, sodomized, and photographed while unconscious. She later awakes somewhere else unaware of what has happened, save for the bruises or lethargic aftermath of the drug.  She may only realize 24 to 48 hours later that she has been sexually assaulted, too late for most examinations to be useful.  GHB can be easily made in the kitchen from industrial solvents and paint remover, and recipes can be easily found on the Internet.  Other rapists of this type use their own barbiturate or benzodiazepine prescriptions, and those employed in health care may use various hypnotics or sedatives they have access to.  Investigation of drug-facilitated rape usually requires extensive medical and expert witness assistance.    

    Another type of insidious offender abuses or molests children.  Victims and their families frequently report the offender was the nicest person you would ever want to meet.  Although a mandated reporter system works well in detecting much child abuse, involving those who work in medicine, social services, psychology, child care, education, and law enforcement, some pedophiles and organized rings of pedophiles go to great lengths at planning and carrying out their crimes.  They are increasingly using the Internet for solicitation and trafficking in child pornography.  About 500 of these types are rounded up every year by the FBI and other law enforcement task forces via investigators posing as bait (e.g., children in chat rooms).  The typical offender is an upper-middle-class, educated white male between the ages of 25 and 45.  Most apprehended offenders will mount an entrapment defense, so it's important for investigators to document everything said or done very precisely.

PROTECTING THE VICTIM

    Nothing is probably more important in a sex crime investigation than protecting the victim, which is an oft-misunderstood phrase that goes beyond interviewing the victim in private.  It means respecting the victim, relating to the victim, building a rapport with the victim, and at least a dozen other things that males cannot ordinarily understand.  For this reason, some police departments prefer or require that female officers be assigned to the investigation of such cases.  While documentation of everything said is important with sex crimes, there has to be some flexibility and room for the victim to "vent", express their emotions, and bounce thoughts and feelings off a sympathetic listener all without worrying about someone recording everything to be used against them later.  Victims of sex crimes often "act out" in strange ways afterwards, and sometimes they are the ones who need protection from themselves.  Subsequent contact between the victim and any potential suspects must be avoided at all costs. 

WORKING WITH THE CRIME LAB

    A sex crime investigation requires continual, ongoing two-way communication between the police investigator and crime lab personnel.  Most crime lab directors know this, and have set up procedures for it.  The problem is that all the different pieces of trace evidence are going to need background control samples, not so much from the time the crime was committed, but from the need to include and exclude all the possible suspects that each laboratory test reveals.  Many instruments used in the kinds of lab tests required are destructive of the evidence, and more evidence needs to be continually available.  Investigators need to be prepared for when a lab analyst calls and says they need more evidence.  You should also be aware that potential suspects in sex crime cases frequently sue police departments for sloppy investigative work by not taking background samples (shoeprints, vacuuming fibers, etc.) from their apartments.  

SPECIAL CRIME SCENE PROCESSING

    The sex crime investigator is going to need special equipment or special expertise.  Extracting fingerprints, debris, or DNA from duct tape or other binding material like rope knots is extraordinarily difficult to say the least.  Obtaining semen evidence, for instance, requires the use of forensic light sources.  Semen has a faint fluorescence under a Wood's lamp (long-wave ultraviolet light), and many fibers have a strong fluorescence under this kind of light.  Both the victim's body and their clothing should be subjected to forensic light analysis.  The victim's clothing not only tells if a struggle ensued (torn or buttons missing), but clothing worn after the assault may reveal evidence (from anal or vaginal discharge).  Don't rely exclusively on semen evidence, as more and more rapists are starting to use condoms.    

    Long-term follow-up on the victim is important for photography purposes.  As with domestic violence, some bruises don't show up until long after the assault.  Bruises are bluish-red after a few hours, purple within a few days, green-yellow at the end of a week, and brown after a week.  Most bruises take 2-4 weeks to disappear.  Documentation of internal damage to the vagina and rectum is going to require the services of a forensic gynecologist (if you can find one) or a medical professional.  They can usually conduct what is called a colposcopic examination (which produces photographs) and detect abrasions, fissures, transections, synechiae, petechiae, and edemas which may indicate microscopic evidence of a rape.  Not too much should be made of these photographic blowups, however, since courts frequently exclude them for being too gruesome, prejudicial, or subject to expert disagreement.

MOTIVE, MEANS, AND OPPORTUNITY

    When developing your theory or theories about what happened, it's important in violent crime investigation to give equal consideration to motive, means, and opportunity.  A lot of the literature on serial killers and repeat offenders is too heavily slanted toward motive and motive-based typologies.  Equally, if not more important, is means (who had the physical strength to commit this particular crime) and opportunity (who had access to or could have been present at the crime scene).  It's helpful to create what is known as a time line, which accounts for the whereabouts of all the principals in the case before, during, and after the crime.  Suspects can be systematically eliminated one-by-one on the basis of opportunity alone.  You can always go back and consider motive and means later.  Criminal personality profiling should be reserved for when there is no apparent motive.

 

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INTERNET RESOURCES
All About Pedophiles by Mark Gado
Anatomy of a Murder
Case Management of a Homicide Investigation
Crime and Clues Group Website
Crime Scene Investigator's Website
Drug-Facilitated Rape and Date Rape Drugs Resources
Dying and Death
FBI National Center for the Analysis of Violent Crime
International Homicide Investigators Association
Medico-Legal Guidelines for Death Investigation
North Carolina's Sex Offender & Public Protection Registry
OVC Report on S.A.N.E. Programs
S.A.N.E./S.A.R.T. Home Page
The Varieties of Homicide and its Research (pdf)
Time Since Death
Criminal Behavior of the Serial Rapist
Understanding Motives and Developing Suspects in Unsolved Serial Rapes

PRINTED RESOURCES
Allison, J. & L. Wrightsman. (1993). Rape: The misunderstood crime. Beverly Hills: Sage.
Axelrod, A. & G. Antinozzi. (2003). The complete idiot's guide to criminal investigation. Indianapolis: Alpha Books.
Ball, J. (2000). Conducting crimes against persons investigations. Austin: Thomas Investigative Publications.  
Burgess, A. et.al. (1978). Sexual assault of children and adolescents. Lexington: Lexington Books.
Dix, J. & M. Ernst. (1999). Handbook for death scene investigators. Boca Raton: CRC Press.
Emsley, J. (2005). The elements of murder: A history of poison. NY: Oxford Univ. Press.
Geberth, V. (2006). Practical homicide investigation. Boca Raton: CRC Press.
Gregory, J. & S. Lees. (1999). Policing sexual assault. London: Routledge.
Groth, N. (1980). Men who rape. NY: Plenum. 
Hazelwood, R. & A. Burgess. (1999). Practical aspects of rape investigation. Boca Raton: CRC Press.
Hughes, D. (1974). Homicide investigative techniques. Springfield: Charles Thomas.
LeBeau, M. & A. Mozayani. (2001). Drug-facilitated sexual assault. San Diego: Academic Press.
Marshall, W.,  D. Laws & H. Barbaree. (1990). Handbook of sexual assault. NY: Plenum.
Morn, F. (2000). Foundations of criminal investigation. Durham: Carolina Academic Press.
O'Connor, T. (2001) "Sexual cannibalism" in The Encyclopedia of Criminology and Deviant Behavior. London: Taylor & Francis
Osterburg, J. & R. Ward. (2000). Criminal investigation. Cincinnati: Anderson.
Pyrek, K. (2005). Forensic nursing. Boca Raton, FL: CRC Press.
Prensky, R. & V. Quinsey (1988). Human sexual aggression. NY: NY Academy of Sciences.
Ressler, R., A. Burgess & J. Douglas. (1988). Sexual homicide. Lexington: Lexington Books.
Sherwood, L. (1997). Human physiology, 3e. Belmont, CA: Wadsworth.

Last updated: Aug 15, 2010

 

 

Investigation of The Violent Crime (Part 1.)

By: Dr. Thomas O’Connor

Program Manager of Criminal Justice and Homeland Security      
                        
Director, Institute for Global Security Studies
Austin Peay State University
601 College Street
Clarksville, TN 37044 

http://www.drtomoconnor.com/3220/3220lect03.htm

     Any investigation into the world of violent crime, such as homicide, suicide, and sex offenses, carries with it some standard procedures of analysis and reconstruction, which we'll discuss here in the context of fairly typical and uncomplicated (exemplar or unequivocal) crime scenes.  There are a few similarities as well as differences with the crime of arson (sometimes treated a violent crime), but the homicide exemplar is so typical of the investigative process as a whole that it's often the only corpus delicti a student needs to know in learning how to investigate (Axelrod & Antinozzi 2003).  Many of the skills involved in conducting a homicide investigation carry over into other crimes, not all, but many. Homicide is therefore considered an exemplar, or good example, to use in the teaching of criminal investigation.  Homicide involves both the study of victimology and suspectology. 

    A few caveats are in order before we begin.  One such caveat has to do with the necessity of speed or haste.  A homicide needs to be investigated quickly because information and evidence will often lose its freshness and become tainted in short order.  Another caveat is that just because you find a body at the crime scene doesn't mean you should launch a homicide investigation.  Homicide is only the sixth leading cause of death in America.  The following table illustrates the odds for average Americans:

Cause of Death	Odds of Occurrence
Disease Heart Attack Cancer Automobile Accident Suicide Homicide	1 in 1.3 1 in 3 1 in 5 1 in 42 1 in 81 1 in 84

    There are times when a preliminary walk-through will tell you that the death is by natural or accidental causes (the top four causes of death), but as a general rule, you should treat all apparent suicides as homicides at first.  With suicides, you may or may not find a note left behind for loved ones, but if you do, you should treat it as a questioned document.  A suicide can, of course, also be accidental or intentional.  The most common accidental ones involve misuse of firearms and drugs.  The most common intentional ones involve hanging and jumping (although sexual asphyxiation is usually classified as accidental).  The special case of drowning is equally likely to be either accidental or intentional.  The following table lists the most frequent order of occurrence for intentional suicides along with a rank order of the most damaging life stressors:

Intentional Suicides	Most Serious Stressors
1. Hanging 2. Jumping 3. Carbon monoxide 4. Poisons 5. Slashing wrists 6. Firearms 7. Drug overdose 8. Drowning	1. Death of spouse 2. Divorce 3. Marital difficulties 4. Trouble with the law 5. Death of friend or family 6. Serious illness or disease 7. Fired at work 8. Retirement

    With homicides, a good rule to follow is make the arrest within 72 hours or the chances of ever making it plummet (Morn 2000).  Another caveat is that it is not absolutely necessary to have a body to launch a homicide investigation.  Missing persons situations are somewhat special, and you should refer to your department's policies on that, but in most cases when you suspect a homicide, it probably is a homicide, and when you suspect an abduction, it probably is an abduction.  If you can't find the body, it's most likely buried or underwater somewhere, unless you're dealing with kidnapping, serial killing, or sexual cannibalism (O'Connor 2001).  Remember that insects and animals will eat up about 60% of the corpse within a week, and unless they are weighted down or stuck on an underwater eddy obstruction, sunken bodies usually become "floaters" by the end of a week.

HOMICIDE INVESTIGATION

    Our society does a pretty good job of tracking dead people and determining criminal causes of death. There's only about 25,000 homicides a year, and you can probably have some confidence in that number as an accurate figure representing the real number of homicides every year.

Homicide is a crime with a pretty high clearance rate; at least 65% of all homicides are solved by arrest of the perpetrator, and some years, the percentage is closer to 85%.  Guns, alcohol, drugs, love, felony-murder, blunt force trauma, knife fights, and strangulation are all associated with homicide. The LAW of homicide needs to be clearly understood:

• 1st degree (cold-blooded murder) requires proof of premeditation, deliberation, and malice (planning, coolness, scheming)
• 2nd degree (hot-blooded murder) requires proof of malice aforethought and intent to do bodily harm (for all practical purposes, malice aforethought is the same as premeditation)
• Voluntary manslaughter (heat of passion) requires proof of provocation and no time to cool off (self-defense is a common defense)
• Involuntary manslaughter (accidents) require at least a reckless disregard of the consequences (insanity is a common defense)

    Treat all cases of death that you come across as a homicide at first, even suicides. Remember that motive, circumstance, and purpose are key elements in determining exactly what type of homicide you're investigating. Be prepared for self-defense and insanity claims. Look at the crime scene for evidence of passion, provocation, and signs of struggle.  Analyze the wound patterns, and try to reconstruct what happened from the fingerprints, bloodstains, and ballistics.

TAKING THE CALL

    It's important to appreciate how death comes to the attention of police, and more importantly, how the case happens to come across your desk. Chances are that someone you know or something you already know about is related to the case, so there's going to be a linkage between this case and one or more of your other cases or something in the police files, like repeated calls for service to an address for domestic problems. You definitely want to know who called the police and exactly when they called and what their voice sounded like over the telephone. A linguistic analysis might be helpful.  You might also want to think about initially consulting with others in your department about what they suspect, but it's best to keep an open mind.

ARRIVING AT THE SCENE

    If you are the first responder (not likely), then exercise procedures called for in the acronym ADAPT (Assess scene, Detain witnesses, Arrest perpetrator, Protect scene, and Take notes).  If the victim is still dying, then take their dying declaration. This is compelling courtroom evidence.  To be admissible, the victim must believe their death is imminent, and what they say must specifically concern the cause or circumstances they believe about their impending death.  If the victim is apparently dead, determine if they are really dead and/or attempt resuscitation. Here's the legal signs of death:

• no respiration
• no heartbeat
• no pulse
• fingernails don't flush when pressed
• eyelids don't close when lifted
• no pupil dilation to light

    If the dead person is missing, ask any witnesses if they know where the body might be. If paramedics, the coroner's office, or Medical Examiner took it, remember that they "own" the body, but you control the crime scene.  Use witness accounts to put chalk lines down where the body was.  Start note taking on characteristics having to do with BODY location, then turn to likely entry and exit points.  Secure the scene after that, and then record your own movements.  If night is falling, and the scene is dark, call the fire department because they usually have excellent lighting equipment. 

IDENTIFYING THE VICTIM

    The body of a dead person is like an encyclopedia of information and knowledge, if only you know how to read it.  The thing to remember is always corroborate, and double-check your identification sources. Don't assume the ID in the victim's wallet isn't a planted ID. Assume that everyone at the crime scene is going to lie to you. There will be the usual cast of characters, and some of them will be serious jokers while others are joking seriously. Confiscate all personal effects of the victim. Look at the victim's clothing and body for stains, laundry marks, monograms, tattoos, etc. Be mindful of planted evidence. Take pictures (facial shots, if not too graphic) and get a family member or somebody to ID the person (if not too graphic). Order fingerprinting, DNA tests, dental X-rays, forensic anthropology on the bones, or whatever you need to do in identifying the body. As a last resort, release a composite sketch to the media: "Do You Know This Person?" 

ESTIMATING THE TIME OF DEATH

    There's always going to be at least two (2) estimates of the time of death -- the police department's official estimate (which may or may not be yours) and the Medical Examiner's estimate. Legally, you should be within 4 hours of being accurate, but this is a tough standard even for the best coroners. Remember that, after death, the body starts to cool down to whatever the outside (or room) temperature is. At death, the body starts to drop from it's normal 98.6 degrees by a factor of 3 degrees the first hour and a factor of 1 degree each subsequent hour.  Then, after 30 hours, it starts to go up again because of the heat generated by decomposition (but this varies by room or outside temperature, so you need to know weather conditions). The following table illustrates:

• 98.6 - time of death
• 95.6 - one hour after death
• 94.6 - two hours after death
• 93.6 - three hours after death
• 92.6 - four hours after death
• 91.6 - five hours after death
• 90.6 - six hours after death
• -------- (to room or outside temp.)
• 66.6 - thirty hours after death
• 67.6 - thirty-one hours after death
• 68.6 - thirty-two hours after death
• 69.6 - thirty-three hours after death
• -------- (to room or outside temp.)

    Rigor mortis is also something you should know about. The body is limp until about 5-6 hours after death, then a hardness begins to set in around the jaw area in front of the ear (temporal mandibular joint area). It then spreads throughout the body for a period of time, and then the body goes limp again. The following chart illustrates:

• stiffness in jaw -- 6 hours after death
• stiffness in upper torso -- 12 hours after death
• stiffness in whole body -- 18 hours after death
• limpness returns to body -- 36 hours after death

    Lividity is the effect of gravity on blood. You'll note that after death, all the loose blood in the body runs down to the lowest point of gravity. If the dead person is on their back, you'll notice these bluish-purple stains on their back. Lividity begins after only 3 hours, and the blood becomes dried after only 12 hours, so lividity is something to look for quick. It tells you if the body has been moved or transported when there are lividity marks in unusual places instead of the lowest point of gravity where you find the body. You can distinguish lividity from a bruise by pressing down on the skin area. Since with lividity, the blood is still in the blood vessels, when you press down on the skin, the skin changes color and turns white (or whatever skin color the person normally has).  Bruises, by definition, are broken blood vessels, so when you press down on the skin area for them, you won't notice any color change; the skin area will just turn another shade of bluish-green.

    The eyes dilate 7 hours after death (dilation is enlargement of the black pupil area). Drugs will also create unusual eye dilations, as will certain poisons, although breath odor is the more likely place to look for poison.  After 12 hours, the whole eye gets cloudy and fish-like. If the person is disemboweled or has thrown up, look at the stomach contents. Anything eaten in the last 2 hours is undigested; food spends 6 hours in the small intestine and 12 hours in the large intestine.  If your victim has been underwater, the average dead person sinks for about 8-10 days (depending on body weight), then they become "floaters" on about the 11th day (although a light person might float after only 7 days).

    Decomposition begins in 30 hours and then starts to rise rapidly after 48 hours. The soapy, mushy remains of a body indicate they've been dead for 3 months. If they are partially mummified, they've been dead for a year. Decomposition is unmistakable by it's smell (the smell of death). You'll be able to see the gases coming out of small gas blisters all over the body, and you won't be able to overlook that bloated greenish tint that the whole body has.

If it's an outdoor crime scene, chances are that small animals have eaten or carried off parts of the body, and even with indoor crime scenes, you're going to have the problem of insects (it wouldn't hurt to know some entomology). North America is home to a particular species (Calliphoridae) of fly known as the blow fly, and they love to lay their eggs on the bodies of dead humans. You'll probably discover bodies teeming with maggots (fly larvae). If you can locate the largest (oldest maggot), measure it in millimeters and add the number two (2), you'll have the approximate number of days since death.  A comprehensive checklist of things for determining the time of death would include the following:

1. the temperature of the body and the rate of cooling
2. the degree of postmortem lividity (hypostasis)
3. the degree of rigor mortis
4. putrefaction
5. insect activity
6. analyzing stomach contents

ESTIMATING THE CAUSE OF DEATH

    Look at the body, how it's posed. Look at the wounds. Look for defensive marks on the knuckles or pieces of skin under the fingernails, anything that might indicate a struggle ensued. Examine the skin’s surfaces for wounds, pinpricks, needle marks. Look to see if anything's in the mouth, vagina, or rectal areas. If your victim's been raped, do a pubic hair combing. Bag & tag any traces of fluids. If your victim's been strangled, determine if there are any ligature marks.  Strangulation marks are horizontal around the neck, and hanging marks are on an upward angle to the back of the head. Determine any poisoning or drugs from odors, color of lips, toes and fingernails.

    The facial expression may tell you something or it may not (most of the time not, as upon death, the facial muscles relax and it is virtually impossible to determine what caused the death).  Experienced investigators have marveled over the peaceful countenance of victims who have undergone horribly painful deaths.  Nevertheless, there are some possibilities that you can go by as long as you realize we're treading more on myth than science here.   Death by firearms may result in a shocked look of expression on the face. After all, that's what you die from in a gunshot injury: shock, either that, or they hit a vital organ.  A strangulation death may have a gasping for air look. 

A blunt force trauma death may have a more painful than peaceful look.  A knife or bleeding death may involve a fairly relaxed look. A drug overdose may be likely to involve a smile on the face, and some types of poisonings (strychnine) produce such violent convulsions that the back arches and this causes the facial muscles to contort into a sardonic grin.  In reality, however, it is unlikely that you will be able to make estimates from facial expression, since this is not a sound method of investigation.  When death occurs, the muscles relax, and are especially more relaxed by the time you look at the body in the morgue.

    If you know bloodstains or ballistics, conduct an analysis of angle and points of trajectory.  Look around for the murder weapon.  It might be down the point of exit.  The coroner's report may or may not be of any use to you. Often, they are full of medical jargon about the mechanism, not the cause, of death.

Read Part 2 of this series

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How Police Find Latent Prints-Part 7-Adhesive-Side Powders (ASP)

By: Don Penven, Technical Support Group

Adhesive Side Powder

Over time, many products have evolved that provide a method of fixing something, and the same is true for the tools used by crime scene investigators.

You have probably heard the old saying, “If it is supposed to move and doesn’t—use WD-40. If it moves and shouldn’t—use duct tape.” These two products have “fixed” a great many problems but one in particular—duct tape—created a whole new problem.

The criminal element has used duct tape to its advantage—it fixes something that moves—mainly the thing that moves is a hapless victim of an armed robbery, sexual assault or kidnapping. Duct tape is used to bind the victims—arms and legs—and it is used across their mouths to silence them.

 Most brands of duct tape have a smooth, non-adhesive side, and this surface is relatively easy for a CSI to develop latent prints using conventional latent fingerprint powders. But, would you believe that the adhesive-side of most tapes with a tacky surface can yield better latent prints than the smooth, outer side?

For a number of years now, CSIs and crime laboratory technicians have been getting extremely useful latent prints from the adhesive-side of duct tape, packing tapes (transparent and opaque), surgical tape—virtually any tape equipped with a soft, non-drying adhesive.

But the development technique is not always a simple matter of just applying a developer of some sort. In many cases the tape is stuck to itself or mangled as it is removed from the victim.  In some cases, the tape is wound on a tool or weapon in several layers also making removal difficult.

 Most of the manufacturers of police field kits that provide the necessary tools to recover latent prints from the adhesive-side also include a chemical that breaks the  stickiness—allowing the tape to be straightened out.

Laboratory experimentation led to the development of adhesive side development techniques. Currently two methods are available to treat the adhesive-side of most tapes equipped with non-drying  adhesives:

• Adhesive-side reagent is a dry, finely milled powder (white or black for good photographic contrast). This powder is mixed with a somewhat thick surfactant solution just prior to use.
• A second method is a ready-to-use, premixed powder in solution.

Adhesive-side powders are used as follows:

 

1. Using the powder/surfactant combination premixed by the investigator, or using the factory mixed solution, apply the powder mixture directly to the adhesive-side of the tape using a soft bristle brush or a cotton “dauber.”

2. Allow the mixture to stand for just 10-15 seconds, and then immediately wash off the excess reagent.

If the perpetrator did come into contact with the adhesive side of the tape, which is highly likely, then the likelihood of his prints being visible is highly probable!

 

Once the processed tape is dry, the developed prints may be photographed (with a scale) and covered with a protective layer of regular fingerprint lifting tape.

Since research on this technique is incomplete, we are not absolutely certain as to what these reagents are acting upon:

1. It could be that the reagent is adhering to the usual, oily residue deposited by the fingertips, or…

2. It could be a thin layer of dead skin from the fingers that the adhesive pulled off, or..

3. It could be a combination of both kinds of residue.

Regardless of the why it works…the fact is that it does work, very well indeed!

Want to learn more about the exciting career of crime scene investigation…Then down load this Training Manual, “The Evidence Collection Mission.”

Download the Technical Information Bulletin on ASP:  

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How Do Police Find Latent Fingerprints—Part 6—Small Particle Reagent (SPR)

By: Don Penven, Technical Support group

A number of special methods for development of latent fingerprints have evolved over the years. While it is not a frequent occurrence, sometimes the surface to be dusted with latent print powders is damp or wet as a result of heavy dew or precipitation.

Small Particle Reagent (SPR) was developed to handle a situation where a wet surface is encountered. SPR is formulated from finely ground chemical particles such as molybdenum disulfide or titanium dioxide mixed with a surfactant and water. A third reagent is a mixture of a fluorescent powder (that may be seen when exposed to ultraviolet (black) light, a surfactant and water.

As is the case when applying latent fingerprint development powders, either the white titanium dioxide or charcoal gray (molybdenum sulfide) is used to get the best photographic contrast.  The ultraviolet reagent is indicated for use on multicolored backgrounds.

Small particle reagents are usually supplied in manual pump spray bottles. The spray is directed toward the area with the best potential for locating latent prints. On vertical surfaces the reagent is sprayed directly above the area being tested, and it is allowed to run down over this area. The reagent may also be used for tray development.

When latent prints develop—due to the reagent particles clinging to any oily fingerprint residue present—a light spray of clean water is directed toward the developed prints to wash away any excess reagent. The latents are then photographed with a scale, and then they may be “lifted” after drying.

An important feature of using Small Particle Reagent is the fact that cleanup after the prints are photographed and lifted is a matter of just wiping the surface clean with a rag or cloth. Fingerprint development powders are typically difficult to remove from many surfaces so Small Particle Reagent is an excellent alternative for outdoor use.

Want to learn more about the exciting career of crime scene investigation…Then download this Training Manual, “The Evidence Collection Mission.” 

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References:

Crime and Clues, “Small Particle Reagent,” <http://www.crimeandclues.com/spr.htm>, April 6, 2009

Lee, Dr. Henry C. and R.E. Gaensslen ed. Advances in Fingerprint Technology, New York: Elsevier Science Publishing Co.; 1991.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

How Do Police Use Insects to Solve Crimes – Forensic Entomology and How it is Used

The concept of forensic entomology goes back several hundred years. But it has only been over the last few decades that scientists haves made a systematic study of the science to determine if it actually is a feasible discipline for use at crime scenes.

According to ” Insects in Legal Investigations:” Insects have existed on earth for about 250 million years; comparatively humans have existed for about 300,000 years.  Such an enormous amount of time has allowed insects to attain a wide diversity in both form and development.  There are currently about 700,000 described species and it is estimated that there may be more than 10 million species of insects yet to be described. 

Forensic entomology is identified as the use and study of insects as their appearance at a crime scene relates to the commission of a crime. It is a study primarily relating to death investigations, but it may also reveal the presence of narcotics, drugs and poisonous substances in a corpse. A trained forensic entomologist may also be able to pinpoint the exact location where death occurred and the approximate time the victim died.

A forensic entomologist can estimate the time of death based on his examination of the growth stages of certain insects—in particular he is looking for evidence of blow flies. A female blow fly will deposit a mass of eggs in the vicinity of any open body orifices or wounds. Over time (8-24 hours) these eggs will begin to hatch into an immature larvae stage (maggots). Maggots have very limited mobility so their feeding range is large enough infestation can result in the quick disappearance of soft body tissue and bodily fluids. These maggots can skeletonize a corpse in a matter of days, removing any tissue or fluids that would permit laboratory analysis.

At and around the crime scene, evidence of the insect infestation is collected. This includes fly eggs, maggots, pupa stage and adult flies. During the pupa stage, the larvae leave the body and burrow into the surrounding soil.  After a short time the pupa emerges from the soil and completes the metamorphosis—becoming an adult blow fly.  Each can be important in their relation to the corpse.  Maggots, pupa, and flies can contain toxins and foreign matters present in the body tissues they consumed.  The presence of specific stages of the cycle can help determine the time of death, which will be discussed later.  And the type of bugs and flies can determine location of the body.  Many times entomologists have identified non-resident species of bugs that indicate the corpse had been moved from one location to the place of discovery post-mortem.  It is important for the investigator to collect all forms of entomological evidence to complete the story.

Once samples from the scene arrive at the lab, the various growth stages are examined and recorded. From these data the Post Mortem Interval (PMI) is determined. The PMI indicates the period from the time of death to the time evidence is collected and examined. Many times this can place the time of death within a day or two of the victim’s actual death.  Other factors are important to note, such as temperature of the soil, air temperature, and surrounding soil and vegetation, as these can all affect the gestation cycle.

If the reader is interested in learning more on this subject matter, you may download a free technical bulletin that describes the step-by step evidence collection procedure as well as the tools and supplies needed by the forensic entomologist at the crime scene. Entomology Manual

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Overview of Latent Fingerprint Development Methods and Techniques-Part 8

Overview of Latent Fingerprint Development Methods  and Techniques

 (Copy, paste and print these pages and keep them in your crime scene kit)

Powders

Powders adhere to both water and fatty deposits. These are generally usefulon newer prints only. Choose a powder to contrast with the background. Theyare useful on any dry, relatively smooth, non-adhesive surfaces. Use afterlaser fluorescence. Powders may be used before ninhydrin and after cyanoacrylate. Results may vary with skill of technician. Lift developed prints by photography or conventional methods.

Silver Nitrate

Silver nitrate reacts with the chlorides in skin secretions to form silver chloride, a material which turns gray when exposed to light. Developed prints must be photographed immediately because the reaction will eventually (and permanently) fill the background. It is useful on paper, cardboard, plastics and unvarnished, light-colored woods. Use it after ninhydrin and iodine. It is not useful on items which have been exposed to water.

Ninhydrin

Ninhydrin reacts with amino acids to produce a purple reaction product called “Rhuemann’s Purple”. It is useful on porous surfaces—especially paper. Development time is up to 10 days, but may be accelerated through the application of heat and humidity. Use ninhydrin after iodine and before silver nitrate. Ninhydrin is not useful on items which have been exposed to water.

DFO

DFO, 1,8 Diazafluoren-9-one, is a fluorescing ninhydrin analog found to develop up to two and a half more prints than ninhydrin itself. It is useful on porous surfaces, especially paper. Development may be accelerated through the application of controlled heat. Use it before ninhydrin. DFO also is useful to develop weak blood stains. It requires a specialized light source, such as the BLUEMAXX™.

Iodine

Iodine fumes react with oils and fatty deposits to produce a temporary yellow-brown reaction product. Iodine is useful on fresh prints on porous and non-porous, non-metallic surfaces. Developed prints must be fixed or photographed immediately because reaction will rapidly fade. Use iodine before ninhydrin and silver nitrate.

Fluorescent Powders

Powders made of fluorescent materials offer the advantages to the limitations of conventional powders. Apply as with conventional powders. Lifts can be made photographically or by conventional means. Fluorescent powders are especially useful on confused backgrounds. An ultraviolet or forensic light source is required.                                                                                                                                    

Physical Developer  

Physical developer is another silver-based developer which reacts to form a dark gray reaction product. It is useful on paper, cardboard and unvarnished, light-colored woods. Use physical developer after ninhydrin and iodine. It is very successful on items exposed to water.

Fluorochromes

Prints may be treated with special dyes called fluorochromes which easily are made to fluoresce and bond with the print deposits. They are useful with inexpensive forensic lights such as SIRCHIE’s BLUEMAXX™. DFO is a fluorescing ninhydrin analog found to develop up to two and a half times more prints than ninhydrin itself. It is useful on porous surfaces. Development may be accelerated through the application of controlled heat. A specialized light source such as SIRCHIE’s BLUEMAXX™ is required. Basic yellow, ardrox and rhodamine are dyes especially useful in conjunction with cyanoacrylate. They require an ultraviolet light source.

Adhesive Side Powder

Adhesive side powder attaches itself to plastic print impressions on the adhesive side of tapes. It produces excellent results on light-colored or transparent tapes, including duct tape, masking tape, plastic surgical tape, foam tape, clear and reinforced packing tapes and labels. This process involves wetting tapes.

Amido Black

Amido black reacts with the proteins found in blood to form a black reaction product. Amido black is useful only on blood-contaminated prints. It is highly sensitive. It is useful on non-porous and some slightly porous surfaces. It sometimes offers successful development of blood prints on dead human skin.

Cyanoacrylate (glue fuming)

Cyanoacrylate fumes react (polymerize) with water and other possible fingerprint constituents to form a hard, whitish deposit. It is useful on most non-porous and some porous surfaces. Cyanoacrylate produces excellent results on Styrofoam and plastic bags. Developed prints may be dusted with powders or treated with fluorescing dyes, such as ardrox and basic yellow to enhance.

Small Particle Reagent

Small particle reagent is a suspension of fine molybdenum disulfide particles. It adheres to the fatty components of skin secretions to form a gray deposit. Developed prints must be photographed immediately because the reaction product is very fragile. Developed prints may be carefully lifted using conventional methods. Small particle reagent is useful on relatively smooth, non-porous surfaces, including wet ones. It may be used in place of, or after physical developer.

Surface Treatments

smooth, Non-Porous

This category includes glass, hard plastic moldings (bare metals are not included) and surfaces treated with paint or varnish. Powders, iodine, small particle reagent and cyanoacrylate and fluorescent dyes may be used on these surfaces.

rough, non-porous

Rough or textured surfaces and grained plastic moldings are included in this category. Regular powders are usually unsuitable on these surfaces. Use small particle reagent, magnetic powders or cyanoacrylate with fluorescent dyes.

paper and cardboard

These surfaces include paper and cardboard (including plaster board) that have not been waxed or plastic-coated. Treat with iodine, ninhydrin, DFO, silver nitrate or physical developer. Powders are generally insensitive to older fingerprints.

plastic packaging material

This category includes polyethylene, polypropylene, cellulose acetate and laminated paper surfaces. Use iodine, small particle reagent, cyanoacrylate and fluorescent dyes and powders. Cyanoacrylate is especially useful on Styrofoam.

soft vinyl (PVC), rubber and leather

These surfaces include simulated leather and cling film. Use iodine, small particle reagent, cyanoacrylate and powders.

metal (untreated)

These surfaces include untreated, bare metal surfaces—not metal surfaces that have been painted or lacquered. Use small particle reagent, powders, cyanoacrylate/fluorescent dyes and powders.

polished or plated metals

The most effective method for latent development on these surfaces (chrome plated, silver, etc.) is a metallic powder such as Silver, Gold or Copper powders. Magnetic powders should not be used on ferrous metals such as iron or steel

unfinished wood

This category includes unfinished wood surfaces—that have not been painted or treated. Treat with ninhydrin. Use powders on smooth wood and silver nitrate or physical developer on light woods.

wax and waxed surfaces

This category includes items made of wax (such as candles) and wax-coated paper, cardboard and wood surfaces. Treat with nonmetallic powders or cyanoacrylate/fluorescent dyes.

adhesive-coated surfaces

This category includes tapes and similar surfaces that are not likely to dissolve in water. Use adhesive side powders.

See catalog pages 90-92: Click Here for Catalog Downloads

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