Crime Scene Training

PrinTips07 Oil Red O

Oil Red O—For Developing Latent Prints on Wet Paper

Sounds like a weird name for a latent print development reagent, but this chemical is finding its way into crime labs throughout the world. Amino acids dissolve in water, and, therefore, fingerprints on porous surfaces that have been exposed to moisture (water) usually do not respond well with traditional methods of latent development chemicals like ninhydrin or DFO. A longtime favorite, the Physical Developer (PD) method, is most often used. 

In 2004, Alex Beaudoin, Services de l’Identité Judiciaire at the Sûreté du Québec, developed a method that made the recovery of fingerprints on wet porous surfaces simple and easy. Specifically, surfaces such as paper and cardboard that had been exposed to water or high humidity were ideal for Oil Red O (ORO). His three-step method displayed simplicity and differed from the multistep PD used in laboratories across Quebec 

Beaudoin conducted tests to compare Oil Red O and physical developer on three types of paper surfaces: thermal paper, white standard paper, and brown kraft paper. Oil Red O was consistently superior to physical developer in terms of the mean fingerprint quality produced on thermal paper. Oil Red O was also shown to be superior for recovering fingerprints on standard white paper. On brown paper, the fingerprint quality was not significantly different between the two methods. This research supports the use of Oil Red O in laboratories for the treatment of wet porous surfaces. And Oil Red O is far less expensive and a lot less complicated to use. 

Formula preparation:

1.54 g Oil Red O powder dissolved in 770 ml Methanol

9.2 g Sodium hydroxide dissolved in 230 ml distilled water

Add the Sodium hydroxide solution to the Oil Red O solution.

Mix & filter the combined solutions. Store in a dark bottle.

 Safety Caution: Methanol (wood alcohol) is highly flammable and toxic. Wear safety goggles, latex gloves and an organic vapor respirator when mising and using this substance. Use only with adequate ventilation or exhaust hood.

Procedure:

1. Immerse the item in stain solution and soak completely.  It is optional to agitate the solution on a

     shaker platform.

 - Ridge detail should begin to develop in 5 min.

 - Weak fingerprints (poor lipidic content) may require 60 to 90 minutes of development time.  

2. Remove & drain item - immerse in a pH7 buffer solution.

3. Remove item from buffer solution - rinse in distilled water.

4.  Dry item at room temperature - or heat in an oven at 50 degrees C (122 degrees F).

Learn more about chemical development methods from the Technical Bulletin: “Overview of Latent Print Development Techniques”

 For alerts when new articles are posted on this blog Sign Up for Email Alerts Here.

JOIN US ON FACEBOOK   
 

PrinTips06 Physical Developer

When all else fails, knowledgeable crime lab technicians turn to Physical Developer

In the 1970s, the new kid on the block of latent print development chemicals was Physical Developer.

As effective as they may be, Iodine fuming, DFO and ninhydrin do not always produce desirable results. The blessing here is that these chemicals do not interfere with subsequent development with Physical Developer. 

On porous materials, a reaction occurs between the lipids, fats, oils, and waxes found in sebaceous sweat and the silver-based liquid reagent known as Physical Developer (PD), to produce a silver-gray deposit visible to the naked eye. Since these sebaceous components are not soluble in water, the PD latent print development technique is particularly useful on wet paper or paper that has previously been wet. When the amino acids in fingerprints have been washed away or failed to react with Ninhydrin, or DFO; processing with PD may still produce identifiable latents. However, PD is time-consuming, expensive, destructive, and has a short shelf life. Therefore, one should only utilize PD as a final process in circumstances where it will be the most effective. (Forensic Magazine) http://www.forensicmag.com/article/comparison-physical-developer-formulas 

The most common commercial formulas for PD include silver nitrate, ammonium iron (II) sulfatehexahydrate and other equally complex reagents. 

Recommended Development Procedure

Some labs recommend a pre-wash of the document in a maleic acid solution:

1. Place the mixed chemicals in a clean glass or plastic developing tray. Do not use metal trays.

2. Immerse the evidence in the solution. Prints should appear in about 5 minutes. Allow development to continue for up to 15 minutes or until the background begins to darken.

3. Rinse the evidence under running water for up to 20 minutes. Air dry after rinsing with document lying flat.

4. Once dry, photograph any visible prints. Be certain to include a scale in each photo.

 Learn more from the Technical Bulletin: “Overview of Latent Print Development Techniques”

For alerts when new articles are posted on this blog Sign Up for Email Alerts Here.

JOIN US ON FACEBOOK   
 

 

 

PrinTips05 Silver Nitrate

Using Silver Nitrate for Latent Print Development

Silver Nitrate has been used for over 75 years as a latent print development technique. In 1937, M. Edwin O’Neill published, “The Development of Latent Fingerprints on Paper,” in which the author mentions the Silver Nitrate processing method. 

Latent print powders were the most accepted means of latent development back then, but developing latents on paper was a difficult task. Porous surfaces such as paper and cardboard tend to absorb latent print residues rendering powders virtually useless, unless the prints were reasonably fresh. 

Silver nitrate is a somewhat light sensitive chemical when dissolved in water or ethyl alcohol and
will darken over several days unless it is stored in amber bottles or locked away in a light-tight cabinet. But its light sensitivity can be turned to advantage when searching for latents on porous materials like paper. 

Silver nitrate combines with the latent print moisture present on a document. The result is that when salt, sodium chloride, is present in the perspiration, which it usually is, the silver combines with the chloride atom of salt to form silver chloride—a highly light sensitive substance. When this occurs, latent prints appear on the paper with dark brown to black ridge detail. 

Ordinary fluorescent lighting will trigger the development process, but bright sunlight or shortwave UV will greatly accelerate it. 

Silver nitrate enjoyed widespread popularity until the 1950s when ninhydrin was introduced to the crime labs around the world. Ninhydrin had a number of advantages over silver nitrate, among which is the fact that once silver nitrate is applied to a surface, it continues to darken even under low light conditions; and cleaning off silver nitrate residues from laboratory apparatus was a major chore. 

Another problem was that the evidence thus processed would continue to darken each time it was exposed to light, and eventually the developed latents would indeed be difficult to discern from the darkening background. 

Few crime labs today use silver nitrate since DFO and ninhydrin are far more effective and do not pose long term cleanup problems. But don’t write off the use of silver compounds—the next PrinTips post will feature Physical Developer. 

Learn more from the Technical Bulletin: “Overview of Latent Print Development Techniques”

For alerts when new articles are posted on this blog Sign Up for Email Alerts Here.

LIKE US ON FACEBOOK  

 

Maritime Crime Scenes-An International Problem

Do Maritime Crime Scenes Differ From On-Shore Crime Scenes

By Don Penven, Tech Support

News stories reporting on piracy along the Somalia coast sparked a world-wide cry for conformity in the training of investigative personnel. The most complex factor is, “Just who is in charge?” The complexity may emanate from a scenario such as this: a hijacked ship may be owned by a Dutch shipping company, flagged in Panama, manned by Filipinos and liberated by German Special Forces.

Coordinating law enforcement activities across the globe is a daunting task, and an acceptable outcome depends of good coordination from investigating agencies and the judicial system where the crime occurs. The US Naval Criminal Investigative Service (USNCIS) and Europol recently joined forces to ensure effective prosecution of the criminal element by conducting a joint meeting in The Hague. These combined forces developed guidelines spelling out how to properly investigate maritime criminal acts.

These guidelines propose a uniformly consistent approach by combining standard, accepted crime scene investigative techniques. Additionally, state-of-the-art forensic examination of crime scene evidence is outlined. The NCIS/Europol alliance looks toward biometric and personal identification techniques such as fingerprint and DNA evidence as causing an increase in the potential for maritime piracy convictions across the board.

It is estimated that nearly 15% of the world’s oil production as well as 20% of world trade passes through the Gulf of Aden. Food supplies and other essentials like medical and manufacturing parts and supplies are also directly disturbed by acts of piracy. Much of all of this traffic, estimates say 80%, is bound for European countries.

Maritime piracy is a major issue causing considerable concern with the skyrocketing of the shipping costs that include insurance rates and basic operational costs. A major source of income for Somalia has become piracy-related activities worth hundreds of millions of dollars.

All agencies cite the need for professional, in-depth training for crime scene investigators (CSIs). While each country offers varying levels of exposure to the basic essentials, The International Association for Identification (IAI), the world’s oldest and largest forensic identification group, offers recognized training and certification programs for CSIs.

The IAI requires training hours that range from a minimum of 48 hours of instruction and a 200-question examination for a Certified Crime Scene Investigator, up to 144 hours of instruction and a 400-question test for a Certified Senior Crime Scene Analyst.

This is all well and good for organized law enforcement, but what happens from the time the crime or act of piracy occurs until a trained CSI reaches the scene or vessel involved? Most often the actual crew of the ship in question can make or break any later criminal proceedings. Experts note that a crime occurring on a freighter would be handled differently than a passenger ship.  It is a much simpler matter to “Secure the Crime Scene” until trained investigators arrive on a freighter, but crew members on a cruise ship will be motivated to “clean up the mess” so as not to alarm, annoy or disturb the passengers.

One major cruise line reported that during a two year period, 102 sexual harassment cases and 113 cases of sexual assault were reported. (http://www.lipcon.com/downloads/RossKleinStatistics.pdf)

CNN reports that, “…though cruise companies don't display crime statistics to the public, they are required to report serious incidents involving Americans to the FBI and U.S. Coast Guard. Salvador Hernandez, deputy assistant director at the FBI in 2007, told lawmakers that the FBI opened 184 cases on crimes that occurred aboard cruise ships between 2002 and early 2007.”

The cruise lines, however, consider those numbers quite small when considering that about 64 million passengers were on-board during that same five-year time frame.

The need for some sort of crime scene training for crew members—particularly those working at on-board security—is a necessity.

Such training is slow to evolve, and the certification requirements for Ship and Vessel Security Officers (SSO/VSO) that serve on cruise ships is mainly based upon regulatory standards that fail to offer any guidance or standards relating to basic law enforcement activities and crime scene investigation protocol. This lack of technical knowledge and needed experience in performing those tasks needed for properly processing crime scenes often hampers any follow-up investigation, as well as any resulting prosecution and resolution of the charges in criminal court.

For more information on crime scene investigation: Download the training manual Evidence Collection Mission   

To receive notification when new articles are posted: Sign Up for Email Alerts 

JOIN US ON FACEBOOK   
  

 

PrinTips04 Ninhydrin Development

Ninhydrin: 2,2-Dihydroxyindane-1,3-dione, a Reagent Sensitive to Amino Acids

Like many of the techniques used in crime labs and crime scenes, ninhydrin (also known as 1,2,3-indantrione monohydrate) was not specifically used for developing latent prints. The first mention of ninhydrin in chemical literature was in 1910. Ninhydrin was a chemical used to detect ammonia or primary and secondary amines (amino acids). When reacting with these free amines, a deep blue or purple color known as Ruhemann's purple is produced. In 1955 a British patent was issued covering its use in developing latent fingerprints.

 Several very effective formulations appeared since the patent was issued. Most were highly flammable and some quite hazardous from a health standpoint.  Today one of the most popular formulas uses the 3M™ solvent—NOVEC™ Engineered Fluid, which is far down the hazardous scale. 

This reagent is packaged commercially in both aerosol and pump spray containers. Many crime labs mix their own solutions and use tray development .Regardless of the application method, both sides of the document or object is saturated with the solution, and then it is allowed to air dry. Development may be accelerated by the careful application of live steam from a steam iron. Development without acceleration of any kind can take 24 hours or longer at room temperature. 

Ninhydrin produces a purple color on most porous surfaces. Several factors, including the amount of amino acids that were contained in the latent print, influence the clarity of the resulting developed latent print. Quite often the visible ridges may be fragmented, while some print donors produce a brilliantly colored print with excellent ridge detail. 

Ninhydrin prints may be enhanced by the addition of a zinc chloride treatment. This will produce fluorescence under UV or blue alternate light sources. 

In many cases, lab technicians will process porous surfaces with iodine (PrinTips-02) fuming followed by DFO (PrinTios-03). If these processes fail to produce usable latents, then ninhydrin development should be used as a follow up. 

Regardless of the chemical process used, good practice is to secure the Material Safety Data Sheets (MSDS) for the product.  Here you will find a list of potential health hazards, first aid treatment and the precautions needed to safely use the product. 

Learn more from the Technical Bulletin: “Overview of Latent Print Development Techniques”

For alerts when new articles are posted on this blog Sign Up for Email Alerts Here.

JOIN OUR FACEBOOK PAGE  

 

PrinTips03 Latent Print Development Using DFO

DFO: An alternative to Ninhydrin

Several very effective methods are available for latent print development on porous materials. Iodine fuming was discussed in PrinTips-02. This article will cover DFO (1,8-Diazafluorene-9-one), which is a Ninhydrin analog, and it too reacts to amino acid residues in latent prints.

 Ninhydrin has been a mainstay for latent print development for several decades. Its original development was to serve as a dye stain for examining body cells under a microscope. It reacts to the presence of amino acids by producing a purple stain. 

But Ninhydrin has its shortcomings, namely, that developed prints may be difficult to see—let alone photograph. The addition of zinc chloride solution adds fluorescence to weak prints.

 In 1989, researchers with the Department of Chemistry, Belfast, Northern Ireland (per the FBI) introduced DFO, which is now commercially available and used in the United Kingdom. Unlike ninhydrin, DFO gives a weakly colored initial print; the main feature of this reagent is its ability to give a fluorescent print without secondary treatment.

 DFO is said to produce 2.5 times the number of latent prints than Ninhydrin. The most often used formula for DFO is as follows:

DFO STOCK SOLUTION

1 gm DFO crystals

200 ml   Methanol

200 ml   Ethyl Acetate

40 ml   Glacial Acetic acid

 Combine and stir with a magnetic stirrer until ALL the ingredients are dissolved.

DFO WORKING SOLUTION

Add Petroleum ether to the stock solution until the total volume is two liters. 

Keep in mind that the DFO prepared working solution has a relatively short shelf life, so this two-part formula will assure that the maximum benefit will be achieved. 

Procedure:

1. Saturate both sides of the document or evidence to be examined. Allow the

evidence to air dry.

2. Place evidence in a heat chamber (DFC100) preheated to 200º F.

3. Remove the evidence after having been exposed to heat for 5-10 minutes.

4. Examine the item for any visible prints. generally, DFO prints will not be immediately visible. if any prints are visible, they will be pale pink in color.

5. Examine the evidence in a darkened room using long-wave ultraviolet light or

an alternate light source.

6. Photograph any visible latents while exposed to UV or alternate light source. Be certain to include a scale in each photo. Note: DFO treatment will not interfere with subsequent chemical tests.

 Learn more from the Technical Bulletin: “Overview of Latent Print Development Techniques”

http://www.sirchie.com/Assets/Manuals/pdf/LP%20Dev'mt%20Tech_TB02-102ENG-REV2E.pdf  

 For alerts when new articles are posted on this blog Sign Up Email Alerts Here.

http://www.sirchie.com/about/news.html

LIKE US ON FACEBOOK

 

PrinTips02 - Iodine Fuming

Latent Print Development Using Iodine Fuming 

It is widely believed that Iodine fuming was the first, or at least among the first chemical methods for developing latent fingerprints. Iodine is a non-metal, crystalline element that was first isolated in 1811 by the French chemist Barnard Courtois. 

The name originates from the Greek word for violet, iodes, and while this element is lustrous metallic gray in color, it gives off a violet/purple gas when heat is applied. In its pure state, iodine is highly toxic by ingestion or inhalation of the fumes. Compounds containing iodine are used in water purification tablets and the radioactive isotope of iodine is used in thyroid gland treatment. Iodized salt is a regular on most dinner tables. 

Iodine occupies a prominent place on the shelves of many crime laboratories. Those purple fumes are known to react with body oils to produce an orange/brown stain. This is especially valuable in the development of latent prints on porous materials such as untreated wood, paper, cardboard and certain types of cloth. 

Iodine fuming works best on prints known to be reasonably fresh, since the body oils tend to disperse rather quickly in porous materials so the ridge detail becomes useless. Thus—ransom or demand notes (this is a stick-up) are likely targets for iodine fuming. If this technique works, the developed prints must be quickly photographed as they are “fugitive,” in that they begin to fade shortly after they appear. 

Iodine fuming is then, the ideal first step in latent development on porous materials. It does not interfere with subsequent processing with DFO, Ninhydrin or Physical Developer. 

 

No complicated or expensive apparatus is needed to start the fuming process. A fuming chamber may be as simple as a Zip-Top plastic bag. Simply insert the document to be examined into the bag with a few iodine crystals, zip it shut and apply heat by cupping one hand over the crystals for 10-15 seconds. Body heat kicks off the “sublimation” process, which converts the solid material into a purple gas. For safety sake, wear latex gloves, safety goggles and an organic vapor respirator.

Learn more from the Technical Bulletin: Overview of Latent Print Development Techniques

For alerts when new articles are posted on this blog Sign Up Email Alerts Here.

 Like Us on Facebook

 

To Catch a Thief

Theft Detection Methods—To Catch a Sneak Thief

By: Don Penven

When a reformed jewel thief is suspected of returning to his former occupation, he must ferret out the real thief in order to prove his innocence. This Alfred Hitchcock thriller, “To Catch a Thief,” was released in 1955. Catching thieves was a much more challenging pursuit back then. But methods some law enforcers use today are simply modernized tricks of the trade used long ago. 

Although the history isn’t clear, thief detection methods using visible stain materials were popular during bygone eras. Visible stain powders were simply very strong dyes modified for use by the police. When a sneak-thief needed apprehending, investigators set traps using physical articles like a wallet, purse or other items that would attract the snatch-and-run thief. 

Visible Stain Theft Detection

Thief detection powder was applied to the surface of these objects using a latent powder-type brush. One advantage of using this method was that a witness need not be present. The thief touches the item and transfers some of the powder onto his fingertips. The dyes used have a strong affinity for water, and the inevitable perspiration of the culprit mixed with the stain, usually blue or purple depending on the formula, would begin to spread. 

The first thing the thief will attempt to do is wash it off. He then very quickly realizes his mistake, as the more water he applies, the more the stain spreads across the bare skin. Yes, after very lengthy periods of scrubbing the stain will weaken and in some areas may even disappear. But a residual remains in the cracks ad creases of the skin. And thus visual identification, even a few days after the theft, by authorities is possible. 

Outdoor use of Visible Stain Materials

Visible stain powders feature mixtures of dye and visible background colors that permit deployment on different colored surfaces. Some manufacturers, seeking a means of using the visible stain method outdoors, offer the dye in an oil-based paste or gel form. This formulation is often used on fire alarms, exterior door knobs and motor vehicles. The one drawback with visible stain usage is that it is extremely difficult to remove any residue from the surfaces to which it is applied. Simply washing it off the surface is … well—you get the point! 

Invisible Sneak Thief Detection

Although an exact date is not available—sometime during the 1960s a new thief detection method appeared on the scene. The basis of this formula is zinc chloride—a fluorophore. Wikipedia tells us:

A fluorochrome (fluorophore) … is used to stain tissues, cells, or materials for fluorescent imaging and spectroscopy. The fluorophore absorbs light energy of a specific wavelength and re-emits energy at a longer (visible) wavelength. The wavelength, amount, and time before emission of the emitted energy depends on both the fluorophore and its chemical environment as the molecule in its excited state interacts with surrounding molecules. 

In less-complex terms, a fluorochrome produces fluorescence when excited by certain light wavelengths—specifically ultraviolet and certain blue light frequencies. Thus, fluorochromes became a viable alternative to visible stain thief detection methods—without the messy cleanup. 

Invisible detection powders and pastes have become the first choice for private and industrial security teams, but the purpose remains the same—to catch a thief or to lead to the identity of an individual tampering with file cabinets, currency (coins and paper bills), computers and other sensitive devices. 

But is it Safe?

From the standpoint of safety, both visible and invisible theft detection methods are essentially non-toxic. The material safety data sheet (MSDS) for one manufacturer’s visible stain powder states under Hazardous Identification Information: If this product is used as indicated it is unlikely that any adverse health issues will occur. Inhalation or ingestion of significant amounts may cause respiratory irritation and/or gastric disturbances. This manufacturer’s MSDS for an invisible stain material offers this same statement. 

Invisible stain materials are currently packaged as powders (for brush application), pastes and also aerosol spray containers. 

Alternate Light Sources

The fluorochrome delivery methods do require an alternative light source in order to actually see the material. Most such products are easily viewed under longwave UV light (365nm-400nm) and blue light in the frequency range of 450nm-470nm. Some UV materials will fluoresce under short wave UV (254nm). The advantage of invisible vs. visible stains in obvious—the perpetrator will not be able to see that the material is on his fingertips or other surfaces that he touches—like his own clothing and other personal items. 

Although catching a sneak thief often depends on decades-old technology it remains a truly effective and low-cost means of nailing the bad guys. 

To keep up with new posts to this blog: Sign Up Here For Email Alerts.

Download the technical information bulletin on visible and invisible detection methods

Join us on FACEBOOK