Crime Scene Training

Avoiding Hazards at the Crime Scene

By: Don Penven, Technical Support

The “Typical Crime Scene”

 Let’s begin with the understanding that “The Typical Crime Scene” does not really exist. Even though the crime involved can be identical to many others (homicide, robbery, burglary, sexual assault, etc.), each crime scene has an individuality unto itself that sets it apart from all of the others.

 Hazards abound at crimes scenes—and your training has made you aware of many of them. When the AIDS virus was drawing attention by its epidemic spread around the world, demand for protective clothing, including antiseptic formulations, latex and nitrile gloves skyrocketed.

 This was a natural response to the many biological evils that are potentially present at a crime scene—and not just AIDS. Even the TV cop shows adopted the “rubber-glove-protocol.”

 The Potential for Other Hazards

 Biohazards must be a consideration at any crime scene, but other just-as-serious circumstances must also be recognized. So what other hazards should be considered? The fully-equipped CSI probably carries a satchel full of potentially hazardous materials—a hazard to him/her and to the others involved in the crime scene investigation.

 The typical crime scene evidence kit contains a number of potentially hazardous chemicals in it. Potentially, you ask? Yes—the hazardous potential is there if the user is not fully aware of the hazards and what steps are necessary to avoid human exposure or contact.

 The following list reviews some potentially hazardous materials:

 Ninhydrin: The reagent is used to develop latent fingerprints on materials manufactured from cellulosic substances to include paper, cardboard, or raw wood. It is applied to a surface in one of two ways:

            1. Spray-The mixture is dispensed from an aerosol can or a pump spray.

            2. Tray development. The liquid mixture is poured into a tray and the items to be tested   are immersed into this liquid.

Ninhydrin aerosols are given a Slightly Hazardous rating but they are highly flammable. Only a trace amount of ninhydrin reagent is present in each aerosol can, and existing regulations state that if less than 1% of a chemical is included, in the total formula, the material need not be mentioned. More on this in a moment!

• Latent Print Powders: The overwhelming majority of latent print powders are considered to have a “Slight Hazard” categorization. While the dust from latent powders may pose a fire hazard, proper use of the powders preclude any possibility of a fire.
• Cyanoacrylate: Cyanoacrylate, or superglue, is considered hazardous—more hazardous than latent powders. This substance is used to develop latent prints on most surfaces EXCEPT cellulosic materials. The fumes from superglue form a molecular bond with the moisture content of latent prints—leaving a solid representation of the latent ridge structure. While the fumes are noxious—they are not hazardous. But superglue can instantly bond the fingers and other body parts together and it generates heat that could inflict burns to human skin.
• Iodine: Iodine crystals produce fumes that react to the fatty, oily residue of latent prints to give an orange to brown representation of the latent ridge structure. Iodine fumes are highly toxic.

 Of course this is barely a smattering of the potentially hazardous materials present in many evidence collection kits. The main point we are stressing here is that before using ANY chemical product or material, the user should acquaint himself or herself with any hazards present. So how does one do this?

 The Material Safety Data Sheet

The material data safety sheet (MSDS) as the name implies, has to do with the safety of a CHEMICAL product. The Office of Safety and Health Administration (OSHA) decreed a number of years ago that the user of any chemical product has a Right To Know about any and all hazards involved with the handling, use and storage of a chemical that contains substances that present a hazard to humans. The crime scene kit will also include hazardous items like a Swiss Army knife or a hacksaw blade, but these physical, non-chemical devices are not covered by an MSDS.

 The MSDS is a document that gives the user a list of hazardous chemicals contained in it as well as specific hazards to the individual, first aid treatments if contact occurs and other concerns, The MSDS will also list hazards to the environment and proper and safe storage requirements.

Here is a snippet of the first page of the MSDS for a particular formulation of ninhydrin spray:

Link to MSDS 201C  http://www.sirchie.com/Assets/msds/201C-202C.pdf

Note: The higher the number (HMIS or NFPA) the greater the risk.

The first thing the end-user should look for is the Hazardous Material Identification System (HMIS) symbol. On this particular MSDS it is in the upper right corner, just below the NFPA (National Fire Protection Association) symbol.

Depending on the software a manufacturer uses, these symbols may appear on the front page, somewhere among the various pages or on the last page.

In addition to this information, further explanations are provided throughout the text. For example: Section VIII of this MSDS explains what basic personal protection is recommended.

VIII. Exposure Controls/Personal Protection:

Personal Protective Equipment:

EYE PROTECTION: Safety glasses with side shields are recommended as a minimum for any type of industrial chemical handling. Where eye contact could occur, chemical splash proof goggles are recommended.

SKIN PROTECTION: For brief contact, no precautions other than clean body-covering clothing should be needed. When prolonged or repeated contact could occur, use protective clothing such as Sol-Vex gloves or other clothing impervious to the ingredients listed in Section 2.

Respiratory Protection: Atmospheric levels should be maintained below the exposure guideline. When respiratory protection is required an appropriate NIOSH approved respirator for organic vapor should be worn. If respirators are needed, assure compliance with OSHA standard 29 CFR 1910.134

The question often comes up as to why a manufacturer uses hazardous materials to begin with. The answer is simply: “Because They Work.” This manufacturer uses formulations recommended by the FBI and other law enforcement agencies. The formula shown here for ninhydrin aerosol solution has been tested countless times and it continues to be a favorite of CSIs and laboratory personnel for over 40 years.

NSI609 http://www.sirchie.com/Assets/msds/nsi609.pdf

Other formulas exist, such as that shown above, but the end-user must always keep in mind that most laboratory chemicals pose a hazard to some degree if proper precautions are not taken. This formula is far less hazardous when used properly. The hazard to firefighters is slightly higher due to the byproducts of combustion.

Special Note: OSHA requires that MSDSs be readily available to all persons likely to use or come into contact with any hazardous materials. OSHA inspectors have been known to make unannounced spot checks on law enforcement agencies.

To secure downloadable MSDSs use the following link. MSDSs are listed here by catalog number: MSDS DATABASE.  http://www.sirchie.com/support/material-safety-data-sheets.html

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New Latent Development Method

Reprinted from ScienceDaily:  http://www.sciencedaily.com/releases/2010/05/100511102121.htm

CSI notwithstanding, forensics experts cannot always retrieve fingerprints from objects, but a conformal coating process developed by Penn State professors can reveal hard-to-develop fingerprints on nonporous surfaces without altering the chemistry of the print.

"As prints dry or age, the common techniques used to develop latent fingerprints, such as dusting or cyanoacrylate -- Superglue -- fuming often fail," said Robert Shaler, professor of biochemistry and molecular biology and director of Penn State's forensic sciences program.

This happens because most of the techniques currently used for developing fingerprints rely on the chemistry of the print. Fingerprints are made up of a mixture of secretions from the body that reacts with different chemicals to form a visible or fluorescent product. Infrared and x-ray imaging also target specific chemicals left behind by the ridges and valleys in the skin.

"Lots and lots of processes take advantage of the chemistry of fingerprints," said Shaler. "This approach looks at the geometry of the fingerprints."

The conformal coating applications suggested by Shaler and Ahklesh Lakhtakia, Charles Godfrey Binder Professor in engineering science and mechanics, use the physical properties of the fingerprint, not the chemistry of the substances left behind. In fact, the researchers believe that even after the fingerprints are developed using the coating, forensics experts could sample the fingerprint material to determine specifics about the person who left the prints.

"The body chemistry of the person who left the fingerprint can tell us some things," said Shaler. "If the suspect is older or younger or a lactating mother, for example."

The researchers used a form of physical vapor deposition -- a method that uses a vacuum and allows vaporized materials to condense on a surface creating a thin film. Normally, the deposition process requires exceptionally clean surfaces because any speck of dust or grease on the coated surface shows up as a deformity. However, with fingerprints, the point is to have the surface material's ridges and valleys -- topography -- show up on the new surface so analysts can read them using an optical device without the necessity of chemical development or microscopy.

"This approach allows us to look at the topography better and to look at the chemistry later," said Shaler. "We wouldn't have thought of this by ourselves, but we could do it together."

One benefit of this approach would be the ability to retrieve fingerprints off fragments from incendiary or explosive devices and still be able to analyze the chemicals used in the device.

The specific method used is a conformal-evaporated-film-by-rotation technique developed to create highly accurate copies of biological templates such as insect eyes or butterfly wings. Both are surfaces that have nanoscale variations.

"It is a very simple process," said Lakhtakia. "And fingerprints are not nanoscale objects, so the conformal coating is applied to something big by nanotechnology standards."

The researchers tested two materials for coating, magnesium fluoride and chalcogenide glass -- a combination of germanium, antimony and selenium. The coating material is heated in a vacuum, while the artifact to be coated is rotated fairly quickly to allow deposition over the entire surface.

"We need to have a coating that is uniform as far as we can see," said Lakhtakia. "But we do not need much of a coating -- in the range of only a micron."

The researchers tried coating a variety of fingerprints on glass and even on tape. They coated pristine fingerprints and those that had been fumed with SuperGlue. In all cases, the coated fingerprints were usable.

Of course, like all approaches, this one can only be used on non-porous surfaces, surfaces that do not de-gas. The equipment used to deposit the coating is a laboratory device, but it can produce the coating in about 15 minutes. The researchers would like to design a portable device that could be brought to a crime scene and produce readable fingerprints on site.

"We are in the process of redesigning the chamber and looking not just at fingerprints, but at other objects," said Lakhtakia. "These would include bullets, cartridges, footprints, bite marks and lip impressions." Shaler and Lakhtakia have filed a provisional patent application on this application.

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