Investigators say the black pistol allegedly recovered from Luigi Mangione, the suspect arrested in connection with the killing of a healthcare executive, appeared to be a ghost gun - a firearm that can be assembled at home.

Police say the suspect had a ghost gun, possibly made with a 3D printer, when he was arrested on Monday. Here's what to know about the increasingly widespread weapons and efforts to regulate them.

The recent use of a ghost gun in a high-profile murder case has reignited the debate over the regulation of these firearms.