The New York Police Department said on Wednesday it has determined that the gun found in the possession of Luigi Mangione, the 26-year-old suspect in the killing of UnitedHealthcare CEO Brian Thompson, matches casings found at the scene of the shooting a week ago in Manhattan.

In a brief response to questions at the end of an unrelated afternoon press conference, NYPD Commissioner Jessica Tisch said police “got the gun in question back from Pennsylvania. It’s now at the NYPD crime lab.”

“We were able to match that gun to the three shell casings that we found in Midtown at the scene of the homicide,” she added. “We’re also able in our crime lab to match the person of interest’s fingerprints with fingerprints that we found on both the water bottle and the Kind bar near the scene of the homicide in Midtown.”

Mangione is in custody in Pennsylvania on weapons and forgery charges. He is fighting extradition to New York, where he faces charges of second-degree murder and firearms charges.

As Mangione was being escorted into the courthouse by police officers this week, he yelled out to reporters that some unintelligible thing was “an insult to the American people.”

Mangione comes from a prominent Baltimore area family that has at one point or another counted among its holdings country clubs, a nursing home and a radio station.

The University of Pennsylvania-educated data engineer graduated with both bachelor’s and master’s degrees in computer science, with a focus on artificial intelligence.

Online speculation surrounding his motives has in large part painted him as a populist hero on a righteous crusade against the wealthy. His digital footprint, however, paints a complicated picture about his interests, which appeared to include fitness regimens and philosophy.

He is quoted on an online book review account as assessing the manifesto of “Unabomber” Ted Kaczynski, as: “impossible to ignore how prescient many of his predictions about modern society turned out.”