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The science behind a shell casing: How the fingerprint of a gun can solve crimes

National database gives leads, links crime scenes, and gets illegal guns off the street
The science behind a shell casing
Posted at 1:36 AM, Jun 21, 2021
and last updated 2021-07-16 20:14:31-04

PUEBLO — Shots are fired. No suspect is immediately identified. But, if one shell casing is found, police have a better chance at solving the crime.

Take for instance a 2017 homicide case in Pueblo. In this particular case, a body was found at the scene, and there was almost nothing for investigators to go on, except for four recovered shell casings. Those casings originally did not turn up any leads through the National Integrated Ballistic Information Network (NIBIN).

NIBIN is a database that contains two-dimensional and three-dimensional images of fired cartridge cases that have been gathered from crime scenes, as well as pictures of shell casings submitted by law enforcement officials who test fire guns collected into evidence. As more local law enforcement agencies participate in NIBIN, there are more images of shell casings submitted, increasing the chances of finding a match for a certain crime. "We get that shell casing result back, and it'll tell us that that gun was used at another scene, which might give us something to go on that we never would have had before," said Detective Greg Egan of the Pueblo Police Department, who is also a Task Force Officer with the Bureau of Alcohol, Tobacco, and Firearms (ATF).

"Each firearm is kind of set up where it's like a thumbprint, a fingerprint. There are no two guns alike."
Detective Greg Egan

Detective Egan said ATF spearheaded NIBIN back in 1999, but there was a nationwide push for the system in 2015. "You have to be all in to make it count," said Detective Egan.

Detective Egan gave News5 a behind the scenes look at how guns are test fired at the Pueblo Police Department. The shell casings are then sent to the Colorado Bureau of Investigations (CBI) in Pueblo, where they are entered into NIBIN. "For the calibers that get entered, it's commonly a 9mm or a 40mm, it will return somewhere around 50-100 images that it says we should take a look at. We'll look at the top 50 for potential leads for our law enforcement partners," said Janel Lyons, a laboratory technician at CBI Pueblo.

Drive bys, shootings, and shots fired incident density
Data collected by the Pueblo Police Department shows the incident density for drive bys, shootings, and shots fired from January to May of 2021.

When it comes to the 2017 Pueblo homicide case, where no leads were instantly sparked by the shell casings found, homicide detectives were able to identify a possible person of interest after months of investigating. The person of interest had been contacted and arrested by the Colorado Springs Police Department. During the arrest, a 9mm pistol was discovered in the car, and through NIBIN it was confirmed to be the murder weapon used in Pueblo months earlier. The person of interest became a suspect in the homicide case, and pleaded guilty to second degree murder. They were sentenced to 47 years in prison.

Detective Egan said the conclusion of the case was a result of both Pueblo and Colorado Springs Police believing in NIBIN. "You went from almost nothing, to the right piece fell into place, to the next piece fell in place, to getting a 47 year sentence. That speaks volumes... Had NIBIN not been there, would we have gotten there? Maybe," said Egan.

Total cases of shots fired
Figures from Pueblo Police show the total number of shots fired cases from January to May of 2020 and 2021.

Detective Egan provided News5 with the total number of cases of shots fired with shell casings in Pueblo for January through May of 2020 and 2021. In 2020, it totaled to 79 cases. Through May of this year, there have been 147 cases. For each year during that period of time, NIBIN has generated around 20 leads.

Through May 2021, there have been 347 total gun cases coming into the Pueblo Police Department. Those are any cases involving a firearm, from menacing to homicide. In 2020, there were 681 cases.

262 firearms have been collected into evidence by Pueblo Police from January to May of this year. Last year, that number totaled to 536 guns.

From January 1, 2021 to June 10, 2021, 110 firearms have been reported as "stolen" in Pueblo. "That number is too high for me. We see on the average of 22 reports a month of somebody reporting their gun as being stolen... Take care of that firearm. Put that gun in a safe. Know where it's at. Don't leave it behind because it's a crime of opportunity," said Detective Egan.

Detective Egan said a majority of shootings in Pueblo are related to gangs, along with a fair amount connected to domestic violence.