CEO Murder Case Puts ‘Ghost Guns’ Back in National Spotlight

The man charged with murdering UnitedHealth Group Inc. executive Brian Thompson on a Manhattan sidewalk last week was arrested with a “ghost gun” in his backpack, refocusing attention on the hard-to-trace weapons and their lethal power.

Ghost guns are unregistered firearms that can be built in minutes from a kit or a 3D printer. They lack the serial numbers stamped on traditionally assembled guns, making it difficult to figure out their origins.

The alleged shooter, Luigi Mangione, was found with a gun and silencer that appeared to be mostly manufactured with a 3D printer, Pennsylvania police said. New York authorities ...