Politicians and Bureaucrats Dont Mix Well with Firearms Forensics
January 10, 2006
by Joseph P. Tartaro
In the past few years, there have been a lot of pie-in-the-sky claims for so-called ballistic fingerprinting. It was viewed as a major way to solve firearms-related crimes by tracing guns through spent shell casings found at crime scenes or bullets or bullet fragments recovered from the victims. California Attorney General Bill Lockyer was a big advocate for what is more properly called ballistic imaging database systems. The Bureau of Alcohol, Tobacco, Firearms and Explosives and Federal Bureau of Investigation (FBI) operate two somewhat different systems for ballistic identification.
Lockyers ardor for ballistic imaging didnt cool when his own experts told him it would not work and would probably make their jobs tougher. He engaged a European scientist in the hope of salvaging his magic wand for crime solutions. However, that expert ended up driving a nail in the ideas coffin.
Now Lockyer is pursuing schemes to have every bullet and case serialized, including by requiring that all handguns be equipped with a system to leave a unique marking or bar code on every cartridge it discharges.
But government politicians and science may not mix as easily as the media headlines suggest.
Fingerprinting is not all that foolproof as the FBI proved in its erroneous tarring of an Oregon lawyer as a suspect in the Spanish train terrorist bombings. DNA testing is also subject to questions and interpretation, which the real crime scene investigators and forensic scientists will be the first to tell you. Actually, it is the expertise of these technical people which can make a case in court for fingerprints, DNA and ballistic matches.
Now, The New Scientist, a magazine published in the land down under, has published a report which cast a cloud over another old method of proving to a jury that a particular suspect fired the smoking gun.
According to the article, a man named Jones is serving a life sentence, in part because of a microscopic particle that Baltimore police found on his left hand. At his trial for murder in 1998, the crime-lab examiner gave evidence that the particle was residue from a gunshot. He claimed Jones must have held or fired a gun shortly before his arrest.
Jones denies this and still protests his innocence. His defense team is appealing the conviction, claiming that the science of gunshot residue (GSR) analysis is not as robust as the prosecution claims, according to an article in The New Scientist by Robin Mejia.
Now, a New Scientist investigation has found that someone who has never fired a gun could be contaminated by someone who has, and that different criminal investigators use contradictory standards. Whats more, particles that are supposedly unique to GSR can be produced in other ways.
Forensic scientists often testify that finding certain particle types means the suspect handled or fired a gun. Janine Arvizu, an independent lab auditor based in New Mexico, reviewed the Baltimore city police departments procedures relating to GSR. Her report concludes: The BCPD lab routinely reported that gunshot residue collected from a subjects hands most probably arose from proximity to a discharging firearm, despite the fact that comparable levels of gunshot residue were detected in the laboratorys contamination studies. The BCPD did not return calls requesting comment.
Some specialists argue for a more cautious approach. None of what we do can establish if anybody discharged a firearm, says Ronald Singer, former president of the American Academy of Forensic Sciences and chief criminalist at the Tarrant county medical examiners office in Fort Worth, TX.
Peter De Forest of John Jay College of Criminal Justice in New York goes further. I dont think its a very valuable technique to begin with. Its great chemistry. Its great microscopy. The question is, how did (the particle) get there?
The New Scientist said GSR analysis is commonly used by forensic scientists around the world. In Baltimore alone, it has been used in almost 1,000 cases over the past decade. It is based on identifying combinations of heavy metals in microscopic particles that are formed when the primer in a cartridge ignites. . . .
There is no standardized procedure to test for GSR, but the organization ASTM International, which develops standards that laboratories can look to for guidance, has developed a guide for performing the technique that was approved in 2001. This states that particles made only of lead, barium and antimony, or of only antimony and barium are unique to gunshot residue. The particles are identified using a scanning electron microscope and their composition analyzed using energy-dispersive spectrometry.
But recent studies have shown that a non-shooter can become contaminated without going near a firearm. Lubor Fojtásek and Tomás Kmjec at the Institute of Criminalistics in Prague, Czech Republic, fired test shots in a closed room and attempted to recover particles two meters away from the shooter. They detected unique particles up to eight minutes after a shot was fired, suggesting that someone entering the scene after a shooting could have more particles on them than a shooter who runs away immediately (Forensic Science International, vol 153, p 132).
A separate study reported in 2000 by Debra Kowal and Steven Dowell at the Los Angeles county coroners department reported that it was also possible to be contaminated by police vehicles. Of 50 samples from the back seats of patrol cars, they found 45 contained particles consistent with GSR and four had highly specific GSR particles. Whats more, they showed that highly specific particles could be transferred from the hands of someone who had fired a gun to someone who had not. This doesnt surprise Arvizu. If I was going to go out and look for gunshot residue, police stations are the places Id look, she says.
Scientists using the technique are aware of the potential contamination problem, but how they deal with it varies. In Baltimore, for example, the city police departments crime lab protocol calls for at least one lead-barium-antimony particle and a few consistent particles to be found to call the sample positive for GSR. The FBI is more cautious. Its protocol states: Because the possibility of secondary transfer exists, at least three unique particles must be detected . . . in order to report the subject/object/surface as having been in an environment of gunshot primer residue. So a person could be named as a potential shooter in Baltimore, but given the benefit of the doubt by the FBI.
Even worse, it is possible to pick up a so-called unique particle from an entirely different source. Industrial tools and fireworks are both capable of producing particles with a similar composition to GSR. And several studies have suggested that car mechanics are particularly at risk of being falsely accused, because some brake linings contain heavy metals and can form GSR-like particles at the temperatures reached during braking.
In one recent study, Bruno Cardinetti and colleagues at the Scientific Investigation Unit of the Carabinieri (the Italian police force) in Rome found that composition alone was not enough to tell true GSR particles from particles formed in brake linings (Forensic Science International, vol 143, p 1).
At an FBI symposium last June, GSR experts discussed ways to improve and standardize the tests. The bureau would not discuss the meeting, but special agent Ann Todd says the FBIs laboratory is preparing a paper for publication that will make recommendations to the scientific community regarding accepting, conducting and interpreting GSR exams.
Singer maintains that the technique is useful if used carefully. I think its important as part of the investigative phase, he says, though not necessarily to be presented in court. But he adds: There are people who are going to be a bit more, shall we say, enthusiastic. Thats where youre going to run into trouble, The New Scientist article concluded.
However, being cautious is not a common trait of politicians and bureaucrats.