Murders aren't happening with Ghost guns, but big bro is scared and they came up with a scary name to scare the general public.

3D printed gun parts were actually from the makers community where they're not malicious, they're customizing grips and handguards and other parts for uniqueness and customization. Reproducing movie and game guns for fun. Capitalist daddy didn't like then making something "for nothing" vs spending Lots of money with retailers and manufacturers, so it slowly became a problem when it caught on and everyone stated making their own.

ONE thing caught attention, and that was 3D printed parts that basically jam a trigger mechanism in Glocks allowing them to fire multiple rounds with a single trigger pull. Now magically these people became awful criminals who are intentionally selling "ghost guns" by the masses that's a huge problem with 1000s being recovered by police... Only I completely made up that whole last part. See if easy to seem believable if there's the slightest credibility involved. I've not seen more than a few dozen maybe recovered guns with 3d printed parts. Most all of them are still regular manufactured parts with 3d "accessories" because you can't print the metal barrel (definitely not reliably) and other parts that would otherwise have a serial number you can now get away without a registration.

Luigi allegedly used a 3D printed gun.