Peek Inside the NYPD's Forensic Unit Where It Investigates Gun Crimes

"This is our little police museum down here," Lt. Denis Burke said as he gave a local news network a tour of the New York Police Department's Forensic Investigations Unit. Among the thousands of confiscated weapons is the gun that killed Jon Lennon and .44 the "Son of Sam" used to attack people in parked cars in the mid-1970s.

CBS New York's Maurice Dubois went behind the scenes into the lab where the officers working may not be apprehending criminals, but they "really do help put bad criminals in jail," Burke said.

After every shooting in the city, CBS explains, this lab is integral in researching bullet fragments in an effort to identify the gun that fired them:

“What were trying to do is match up the striations that are left behind when the gun is fired,” Lt. Burke said.

Like a fingerprint, each gun barrel leaves a distinct pattern on the bullet, but sometimes the data base is no match for an experienced detective’s memory.

“We’re sort of like fitting a puzzle together,” Det. Jonathon Fox said.

Watch the CBS report with footage on the inside:

Last year, more than 10,000 pieces of gun-related equipment and 6,500 firearms made it through the lab.

As you might imagine, the work is very tedious and methodical but, as Det. Joseph Cummings told CBS, "it actually does give you a pretty good feeling that you could be helping the detectives out here looking for the bad guys."