The 3D-printed gun found on the suspect in last week's killing of United Healthcare CEO Brian Thompson matches shell casings found at the site of the shooting, NYPD Commissioner Jessica Tisch said Wednesday.

Former FBI agent Scott Duffey stops by FOX 29 to help break down the latest developments in the case against alleged CEO killer Luigi Mangione, who is being held in a Pennsylvania state prison.

Shell casings recovered at the scene of the slay came from the gun Mangione was carrying when nabbed five days later, cops say.

This image release by Pennsylvania State Police shows a video image of Luigi Mangione, a suspect in the fatal shooting of UnitedHealthcare CEO Brian Thompson, at a McDonald's in Altoona, Pa., Monday, Dec. 9, 2024. (Pennsylvania State Police via AP) AP

There have been plenty of jokes flying about Luigi Mangione since he was arrested for last week’s shooting of UnitedHealthcare CEO Brian Thompson. The health insurance executive was gunned down in a shooting that was caught on video outside of his New York City hotel, before the suspect fled the scene on hopped on a bus out of the city.

Suspect identified as Luigi Mangione, a Maryland native with ties to San Francisco, California whose last known address was in Honolulu, Hawaii.

The 26-year-old remained behind bars in Pennsylvania, where he was being held without bail after being arrested and charged earlier in the day with possession of an unlicensed firearm, forgery and

Fingerprints belonging to the man charged in last week's murder of UnitedHealthcare's CEO match those found on a water bottle recovered not far from the scene, sources say.