MIAMI – CBS News Miami visited the Miami-Dade Police Headquarters to investigate how local authorities solve gun-related crimes, following a report from our sister station in Minneapolis about delays with the ATF’s E-trace system.

While the E-trace system has caused case delays elsewhere, Miami-Dade Police use advanced forensic science and a national database to develop investigative leads.

CBS News Miami was given rare access to the department’s forensic lab to see how their process works.

The first room on our tour was the shooting lab, where firearms recovered from crime scenes are tested. The gun we saw was used as part of a simulated mock crime scene event to illustrate the entire process. After the specialist in the shooting lab loaded the gun, he put the firearm in position to fire into a specialized water tank.

“The water slows down the bullets so we can recover it, and use the markings on that bullet and compare to any evidence that’s recovered,” shared Gabriel Hernandez, who helps lead the lab at Miami-Dade Police Headquarters.

He’s worked there for 19 years, overseeing a group that’s generated thousands of leads to help solve Miami-Dade criminal investigations.

“If there’s a gun that’s been recovered, then the main question is, is this the gun that fired those casings and/or bullets,” shared Hernandez.

The mission: match the firearm with the ammunition recovered.

After the test bullets were fired, we moved to a different lab section with microscopes. Under a microscope, we saw how they closely examined test-fired bullets from the shooting tank compared to one recovered from our mock crime scene.

“And then compare those markings on those two items under one field of view,” added Hernandez.

“Markings all along the edge here are a signature of that firearm, unique to that firearm much like a fingerprint is to a person.”

In this case, we saw it was a perfect match.

However, in real cases, detectives do not always recover a gun from a shooting investigation, or the ballistic evidence collected does not match the firearm found.

When that happens, the department turns to technology known as NIBIN. It stands for the National Integrated Ballistic Information Network, run by the federal government.

This national computer database stores recorded ammunition markings from evidence collected at crime scenes nationwide for comparison.

In this part of the lab, we witnessed them taking a bullet and inserting it inside a computer that then scans it into the database for record keeping.

“We have thousands and thousands of images in the system,” said Hernandez. “It captures those images, and then they’re compared to the entire database of all the casings and all the other test fires that we’ve entered into the system. The database sends back a list of potential matches.”

A trained forensic expert then compares the markings on a computer to see if there’s a match to other ballistic evidence collected from another crime scene, helping to solve other investigations.

They can process the evidence that’s been cleared and submitted to the lab in just a few hours.

MDPD shared this statement with us:

“In 2001, the Miami-Dade Police Department started imaging casings in the National Integrated Ballistic Information Network (NIBIN), which is run by the ATF. Prior to that, casings were imaged in DRUGFIRE, a system run by the FBI. Currently, there are over 11,000 NIBIN leads from casing evidence entered at the MDPD Forensic Services Division Crime Laboratory. Approximately 600 NIBIN leads have been made since the beginning of 2024.”