Panel advises against gun markings database

WASHINGTON (Reuters) - An expert panel rejected the idea of a database of ballistic markings from new and imported guns sold in the United States, saying on Wednesday it may not yield practical leads to solve crimes.

Maryland and New York have such databases for guns sold or made in those states, and the U.S. Justice Department asked the National Research Council to assess the wisdom of creating one nationally.

The council's panel of experts said the basic assumption behind forensic firearms identification -- that a gun leaves marks on bullets and cartridge cases unique to that weapon that remain unchanged after repeated firings -- has not been proven.

So-called toolmarks are created on cartridge cases and bullets when a gun is fired. These microscopic marks can be formed when a bullet scrapes against grooves on the inside of the gun barrel or when high gas pressure forces the walls of a cartridge case against a gun's firing chamber.

Images from more than a million guns would be entered into such a database every year and many of these would have similar toolmarks, according to John Rolph, a statistics professor at the University of Southern California who headed the panel.

"Because current technology for collecting and comparing toolmarks is not sufficiently precise in distinguishing extremely fine marks among some of the images, searches would return too many possible matches to be practically useful," Rolph told reporters.

"In addition, the type and brand of ammunition used in the initial firing of a gun would not necessarily be the same as the ammunition used later in a crime," meaning this could be a source of error in generating possible matches, Rolph added.

With such a national system, once a gun is sold, images of cartridge cases from a test firing of that gun would go into a database. Investigators who collect ballistic evidence at crime scenes could search the database for possible matches.

The report did not weigh the admissibility of gun toolmark evidence in court. But the panel advised firearms examiners against stating that "matches" of ballistic evidence identify a particular gun to the exclusion of all others.

The panel appointed by the council, which advises U.S. policymakers on science, engineering, technology and health issues, did find that current ballistic imaging technology can produce important leads to investigate crimes.

While opposing a national database for images of ballistic markings from new and imported guns, the panel urged further research on a technique called "microstamping" in which unique marks are imprinted on guns or ammunition that later may be useful in tracking weapons used in crimes.

Computerized imaging has enabled law enforcement authorities to place toolmark images in databases of crime-related ballistic evidence and search for images of bullets or cases with similar marks since the 1980s.

The committee urged improvements for an existing ballistic image database administered by the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives that contains images from crime scenes and criminal suspects' weapons.

(Editing by Maggie Fox and Vicki Allen)