The arrest of Luigi Mangione, suspected in the brazen killing of UnitedHealthcare CEO Brian Thompson, is certain to bring renewed scrutiny to the debate over restricting the capabilities of 3D printers to make so-called “ghost guns.” Mangione, apprehended Monday at a Pennsylvania McDonald’s, was carrying a 3D-printed black pistol with a silencer that is also believed to be made on a 3D printer. Police believe they were used in the shooting of Thompson in Midtown Manhattan last week.

Initially, investigators speculated the gun used in the ambush was a conventional firearm, quite possibly a bolt-action pistol with an integrated suppressor, such as the B&T Station Six or a WWII English Welrod pistol. Some commentors speculated it was a standard semi-auto that was jamming, so had to be cleared with each shot when it failed to cycle as displayed in surveillance video of the way he fired the weapon. However, the discovery of the ghost gun—assembled without a serial number—may explain the functional limitations of the firearm if not properly created. But it will also no doubt stoke the flames of anti-gun politicians and leaders.

Police are not yet certain if the gun used in the shooting was a ghost gun, but they suspect it was and are currently testing the firearm.

“It may have been made on a 3D printer, the capability of firing a nine-millimeter round,” said NYPD Chief of Detectives Joseph Kenny. “Obviously, that will come out during our ballistics testing.”

3D-printed guns can be assembled at home and are part of a longstanding tradition of gun enthusiasts who enjoy building their own firearms. The ease-of-use and prevalence of 3D printers, however, have led to an increase in the guns’ use in crimes. In New York City, police recovered 382 ghost guns this year, a 154% increase from 2020, ABC 7 in New York City reports. Mangione’s pistol reportedly had a metal slide and plastic handle with a metal threaded barrel.

The case, involving a high-profile target and a self-manufactured weapon, is expected to intensify scrutiny of ghost guns nationwide. Gun enthusiasts who build these weapons, often for sport or self-defense, may face increased regulation and enforcement as a result.