Ballistic scientists analysing minute bullet scratches

WHEN it hit him, the .223-calibre bullet was moving about 2,000mph, and as it entered his body, it splintered.

Shards of lead tore through his intestines and stomach, severed his pancreas and grazed one of his kidneys. The biggest fragment ricocheted upward and stopped in his chest.

As the unidentified man, shot on Saturday night outside a Ponderosa restaurant in Ashland, Virginia was rushed to a hospital in nearby Richmond, bullet fragments were scattered inside his torso like tiny pieces of confetti. That meant, as an emergency room nurse at the hospital put it, “his body was considered a crime scene”.

So, as doctors worked to save the man’s life, they knew any bullet fragments they removed from his body would be important to law enforcement officials investigating the shooting.

Finally, on Sunday night, during the victim’s second surgery, doctors removed a small chunk of lead, placed it in a specimen jar and gave it to law enforcement officials waiting at the hospital.

The fragment was rushed to the national ballistics laboratory in Rockville run by the federal Bureau of Alcohol, Tobacco and Firearms. It was compared with bullets or fragments from a dozen shooting incidents attributed since October 2 to a deadly sniper roaming the Washington region.

Yesterday afternoon, authorities announced what many people had suspected: The man outside the Ponderosa had been shot by the sniper.

The 12 previous shooting incidents - in Montgomery, Prince George’s, Spotsylvania, Prince William and Fairfax counties and in the District - were highly similar. In each incident, a single rifle shot was fired from a distance. In one case, a bullet whizzed through a store, injuring no-one. In the 11 others, nine people were slain and two wounded, all apparently at random, while going about ordinary activities.

With no solid witnesses, the bullets and fragments recovered from the victims and the store have composed the bulk of the investigators’ hard evidence and allowed them to connect the shootings to the same rifle.

Including the Ashland case, ballistics matches were made in all but two of the attacks in which people have been shot. In the other cases, the bullets were too damaged to be accurately tested.

When magnified more than 100 times, unique scratches left on a bullet by the weapon it was fired from can be measured to the thousandths of an inch.

The inside of a gun barrel is lined with twisting grooves designed to put a spin on bullets.

As the bullet squeezes through the barrel, the grooves leave unique marks in the lead, some of them invisible to the eye.

“Those minor scratches that are placed on the bullet as it travels down the barrel is what makes it uniquely identifiable to the weapon that fired it,” said Susan Narveson, director of the forensics at lab of the Phoenix Police Department and the president of the American Society of Crime Lab Directors.

Once the bullet fragment is turned over to a ballistics lab, technicians enter a digital image of the tiny markings into a computer database called the National Integrated Ballistic Information Network. The computer then spits out likely matches, which examiners further study under a microscope.

The ballistics evidence from the Ashland shooting was linked by lab technicians on Monday to the earlier sniper incidents in which bullets or fragments were recovered, the ATF said.

The technology, also called ballistics fingerprinting, is used by the ATF and 160 crime laboratories across the country.

Lab analysts prefer to have the entire bullet, but a fragment as small as two square millimetres can be enough, said Pete Gagliardi, vice president of Forensic Technology Inc, the Montreal-based manufacturer of the Ballistic Imaging System.