Courts & Crime

Stakes are high as doubt is cast on forensic lab techniques

FORT WORTH, Texas -- See this gun.

Hold it.

After examining the gun and an evidence bullet, a firearms examiner tells you that this was the weapon used in a shooting.

As proof, he shows you the observations and comparison he has made using a microscope that reveals patterns of striations on the bullet. If the patterns correspond from test-fire to test-fire and to the bullet, the examiner says the bullet is "a match" to the firearm.

Firearms analysis has helped convict Texas defendants for decades. Others’ crimes were purportedly exposed by dog sniffing, hairs at crime scenes, latent fingerprints and gunpowder flakes. Now it’s up to the state commission tasked with investigating crime labs to move forward on a charge that will draw intense scrutiny to such analyses.

The Texas Forensic Science Commission had planned this month to begin a series of discussions about a national report that opened a Pandora’s box of questions about crime lab techniques. The National Academy of Sciences — advisers to Congress and the president — reported that conclusions about bullet matching are opinion, not fact. Most other identification methods widely used by forensic scientists, the panel advised, also haven’t been validated.

How did a scientifically unproven method receive the blessing of the FBI and forensic "experts" across the nation and other crime lab methods become so widely accepted?

"In a nutshell, these people aren’t scientists," said Jay A. Siegel, a member of the academy, which was established by President Abraham Lincoln to advise the nation on far-reaching questions of science and technology. "They don’t know what validation is. They don’t know what it means to validate a test."

Bullet matching — a practice that takes place every day in Texas crime labs — isn’t reliable, Siegel said, and no studies have been conducted to prove the extent to which firearms marks are unique.

"It’s not possible to state with any scientific certainty that this bullet came from any weapon in the world," said Siegel, who is the chairman of the department of chemistry and chemical biology at Indiana University-Purdue University Indianapolis and director of the Forensic and Investigative Sciences Program.

Other identification methods — including tying hairs to suspects, guns to criminals and blood spatter to crime scenes — lack protocols and standards that legitimize such practices as "scientific."

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