The Associated Press
COLUMBUS, Ohio (AP) -- Though a sniper's bullet hits its target in an
instant, it can take forensic experts days or weeks to match the
projectile to its firearm or another bullet.
Microscopes will magnify the bullets and computer software can
indicate similarities between digital images, but links must be
verified by a human investigator comparing hundreds of tiny scratches
and taking notes by hand.
It has been more than six weeks since a 62-year-old woman was shot
and killed while a passenger in a car traveling on Interstate 270 on
the city's south side. It is one of 18 shootings in the area over the
last several months that has been linked by authorities.
A task force has connected seven recovered bullets from the
shootings, and investigators have interviewed hundreds of people
without identifying a suspect.
No weapons have been recovered from any of the shootings, and the
task force won't say how many weapons it has tested from those who
have been interviewed.
The time-consuming process of discerning a bullet's "fingerprint"
sheds light on why the probe has dragged on. Experts say forensic
testing of a bullet can take anywhere from a few hours to more than a
At the Columbus Police Crime Lab, which has handled all ballistics
testing from the investigation, only one analyst is trained to
compare bullets, said Jami St. Clair, the lab manager.
The analyst had to give up vacation time last year, and the testing
of bullets in other cases has lagged because of the investigation,
said Sgt. Brent Mull, a police spokesman.
"He's been working seven days week," St. Clair said. "I think he took
Christmas off; that's about it."
Each bullet fired from a gun retains a pattern of scratches from
imperfections in the gun's barrel. The unique patterns can be used to
match bullets to one another or to a specific firearm.
Through a powerful microscope, the surface of a tiny, round bullet
appears flat and furrowed -- like a metal washboard but more
"It's probably the microscopic examination that takes the longest,
but there's all kinds of time elements that are involved," St. Clair
said. "The analyst has to take notes and visually examine it. He has
to fire the suspected weapon in order to collect the bullet to
compare it to an unknown. Reports have to be written and typed and
The process begins well before the bullet reaches the lab. Two days
after a house was shot on Dec. 15 -- one of the 18 shootings to be
connected -- a technician on a ladder spent more than an hour
carefully examining two bullet holes. Gusts of frigid air blew across
the front yard as he used pliers to remove siding around one of the
quarter-sized holes and later chipped at the wood beneath with a
hammer and chisel.
Such deliberate work is required so the bullet isn't damaged further,
a forensic investigator said.
"Whenever there's damage to the bullet, the damage can result in a
loss of those individual characteristics. The more characteristics
you have, the easier it is," said Ron Dye, a forensic scientist with
the Ohio Bureau of Criminal Identification and Investigation who has
helped confirm matches for the investigation.
Once a bullet arrives at a crime lab, analysts -- using their eyes or
a relatively low-powered microscope -- look for blood, dirt or other
evidence that could be swabbed for testing by a DNA specialist.
Analysts obtain test bullets by firing handguns into a 7-foot long
metal tank of water, which slows the bullet while preventing further
damage that would obscure scratches from the barrel.
Rifles fire bullets with greater force, so investigators use a 4-foot
long steel box filled with quilting cotton for test firing.
Dye said investigators sometimes must fire several bullets to get a
match comparable to one recovered from the crime scene.
Comparisons are done under a powerful microscope that allows two
bullets to be viewed side by side. The forensic investigator uses
sticky wax to attach the bullet to a crescent-shaped aluminum device,
about 4 inches tall, which holds the bullet under the microscope
lens. Tiny knobs and gears on the device allow the investigator to
twist and turn the bullet so its scratches line up with those of its
A dividing line separates the images of the bullets, but it can be
configured so it appears to be an image of a single, continuous
"There are horizontal characteristics that tend to ignore the
dividing line that gives you the illusion you are looking at one
bullet instead of two," Dye said in an interview in the bureau's lab
in London, west of Columbus.
A computer database, similar to what's used for fingerprints, allows
authorities to compare digital images of bullets from across the
country. But the evidence has to be examined side-by-side by a human
to verify a match.
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In 2003, the Columbus lab used the database, known as the National
Integrated Ballistics Information Network, to compare bullets 1,965
times, which led to 86 matches, St. Clair said.