Filing forensics

Analysts initiate less mainstream databases for law enforcement use


     The Glass Evidence Reference Collection came in handy for the Miami-Dade Police Department in solving a hit-and-run accident on Miami Beach in 2002. A woman crossing the street had been struck by a BMW, and the vehicle was abandoned at the scene. The owner of the vehicle denied any part in the crime and said the car must have been stolen, Almirall says. After police recovered glass evidence from the owner's house, Almirall analyzed it and compared it to glass from the scene, showing that they came from the same source. The owner of the BMW went to trial, pleaded guilty and is currently serving a 12-year sentence, Almirall says..

     The database is maintained by Almirall and the institution, but exists as a reference to prove the uniqueness of glass based on its chemical elements. Because of the complicated analysis process and the expensive equipment necessary to perform it, the value of the database is not in its searchability, but in its power to show the evidential meaning of glass evidence, Almirall explains. He says individual cases are accepted on a case-by-case basis to do analyses for the law enforcement community. For more information on the glass reference collection, e-mail Almirall at almirall@fiu.edu.

Chemical fingerprints

     The Ignitable Liquids Reference Collection (ILRC) also differs slightly from traditional searchable databases. Unlike AFIS or CODIS, the information on ILRC's online database is more specialized and technical, geared toward fire debris analysts' and chemists' use. The database includes chemical information such as a product's hydrocarbon range, predominant profile and thumbnail pictures of the product's major components for crime labs to utilize in identifying potential liquids used to accelerate a suspicious fire, which is how Judi Hoffmann, a 20-year chemist with the Montana Forensic Science Division, makes use of the ILRC.

     "New formulations that have never been seen before are constantly being developed to make better use of petroleum products," Hoffmann says. "[Manufacturers are] always trying to find a way to use every part of the crude oil. For instance, if one product needs to be fairly clean and they do some processing, they then want to use that one clean product and [the byproduct]."

     The database, which is maintained by the National Center for Forensic Science (NCFS) through the University of Central Florida, holds chemical profile information on liquids that could be used to accelerate a fire. The ILRC database has gas chromatograph and mass spectral data of nearly 500 ignitable liquids which have been classified by fire debris analysts throughout North America. It also contains pertinent product information about the ignitable liquid. Mary Williams, the coordinator of research programs and services for NCFS, explains that ignitable liquids are purchased, analyzed by gas chromatography/mass spectrometry and the data is entered into the database and classified. The frequency of updating the database depends on the availability of new samples and the time afforded by the practicing fire debris analysts on the committee.

     The project was brainstormed by the Technical Working Group for Fire and Explosives (TWGFEX), a professional organization of examiners from around the country. Members — including Hoffmann, who co-chairs for TWGFEX's Ignitable Liquid Reference Committee — thought the forensic community would benefit from a searchable database of ignitable liquid products that one may come across in fire investigation casework. In addition to the searchable database, the ILRC also maintains a repository of the products in its database, which can be ordered for a nominal fee. This way, Hoffmann explains, analysts can test the sample on the same equipment used to analyze evidence, which is an evidentiary requirement for many states. Analysts can use the sample to compare with case evidence analyses using one's own instrument under that jurisdiction's operating conditions.

     Though laboratories that analyze fire debris have their own standards on hand, they may not be comprehensive or match the evidence, due to the ever-changing product compositions. For example, in one suspicious fire case, Hoffmann found a product that was not in her pantry of standards at the Montana Forensic Science Division. She says she used the database to find a product that was almost identical; a store brand of charcoal starter fluid.

     "I went down to the store and bought some," Hoffmann says. "When I came back and analyzed that, it actually looked different than what I had in my case work. I was able to contact the repository and have them send me a sample from the database. I analyzed that, and it matched exactly."

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