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The trial of the alleged Grim Sleeper serial killer this year featured a wide variety of evidence, including DNA. One of the key pieces were ballistic comparisons showing the same .25-caliber handgun was used to kill seven of the victims. But the defense attorneys for Lonnie Franklin, Jr. presented an expert who called into the question that very analysis – saying that the 2-D comparisons made by the police experts were subjective – and didn’t have enough of a scientific basis.

A massive undertaking is underway to enhance ballistics analysis – and get those quantitative comparisons for future prosecutors and defense attorneys.

A 3-D, open-access database was unveiled last week by the National Institute of Standards and Technology.

The goal: to definitively match bullets, shells casings and guns, based on the minute markings left by the weapon’s breech face and firing pin, said Robert M. Thompson, the senior forensic science research manager at NIST’s Special Programs Office.

Using advanced 3-D topographic surface maps, the advanced matches allow for more in-depth comparisons, Thompson told Forensic Magazine in an interview.

“This is the seed,” said Thompson. “This database has not only the underpinning for research and advanced comparisons – but also the foundations for the future.”

The National Integrated Ballistics Information Network, or NIBIN, is currently the standard comparison tool. NIBIN was launched in the 1990s by the Bureau of Alcohol, Tobacco and Firearms. The database, much of it which relies on 2-D pictures, has approximately 2.8 million images of ballistic evidence on file, and has produced 74,000 hits over the years.

But with the advent of DNA – and juries demanding concrete numbers from experts – subjective comparisons, even ones made by a certified expert, are not necessarily enough for juries conditioned by true-crime TV.

“When an expert testifies that two bullets are a match, the jury wants to know, ‘How good a match is it?’” said Xiaoyu Alan Zheng, a mechanical engineer and researcher at NIST, in a statement released by the agency.

New 3-D topographic surface maps of the breech face and firing pin impressions left in the primer at the base of the cartridge case will supply the information for the new open-access NIST ballistics database. (Source: National Institute of Standards and Technology)

Critics contend that subjective ballistics is not statistical, like DNA has become in recent years. Gun barrels manufactured consecutively on a production line may be extremely similar, or a gun could wear down over many uses, essentially changing its forensic signature, some claim.

The new database is an attempt to full account for all the potential variables – and then tell juries how exact the comparisons are, compared to every other firearm known to authorities, NIST experts said.

Thompson, a veteran criminalist and firearms examiner who worked with the ATF, and the Oregon State Police, was involved in the establishment of NIBIN. This new database, however, answers some of the criticisms, implicit and otherwise, made in a 2009 National Academy of Sciences report which critiqued the state of forensic sciences at use in the American legal system.

READ MORE: Suspected Serial Killer 'Grim Sleeper' Defense Targets Ballistics Evidence

But this concept, allowing multiple agencies to pitch in and upload their own standard information, could prove true the adage: “many hands make light work.”

“It’s almost like crowd-sourcing the ballistics database,” Thompson said.

The courtroom is still years away. So far only 1,600 test fires have been uploaded into the new dataset. Thompson estimates that it will take five years to get a big enough “population” of firearms to start making advanced statistical analyses with algorithms. Part of the bottleneck is due to the relative scarcity of the microscopes needed to complete the standard analysis: only a handful are available currently to U.S. law enforcement agencies. Once the sampling is big enough, it may take another five years for the database to appear in American courtrooms, he expects.

Until then, existing ballistics comparisons by trained experts will continue, as it has for most of the last century. Franklin, the Grim Sleeper, was convicted on multiple counts of murder earlier this year, based partly on the ballistics testimony – even though it was two-dimensional.

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