Luigi Mangione, the suspect charged with murder in the fatal shooting of UnitedHealthcare CEO Brian Thomson allegedly had a homemade gun, known as a ghost gun, when police arrested him on Monday.

The handgun that police say may have been made with a 3D printer, is similar to the gun that shot and killed Thomson.

Ghost guns are untraceable. They can be assembled at home or 3D-printed, and don’t have a serial number that can be tracked. They don’t require a license or background check to be obtained.

“That’s the beauty of it for the criminal and that’s the stumbling block for law enforcement,” said Mark Mendelson, a former homicide detective in Toronto.

There are two common forms to obtaining a ghost gun, Mendelson said.

People can legally purchase individual gun parts online -- in some cases there are do-it-yourself kits, which can be assembled at home. Sometimes, additional parts are 3D-printed to fill in the missing pieces. Other times, the entire gun can be 3D-printed using software obtained on the dark web, according to Mendelson.

“If you know where you're going, you'll find it. There will always be somebody ready to sell it to you,” he said.

Ghost guns in Canada

It is illegal to manufacture firearms in Canada unless you have a business license to build them.

Ottawa has taken steps to specifically crack down on ghost guns.

Officials work with Canada Border Services Agency to help intercept imported parts for homemade guns. Recently, the government made it illegal to possess or distribute 3D printing software used to manufacture guns.

But it’s not illegal to own a 3D printer.

3D printers are sold for as cheap as $300 online, but those in the printing business say criminals likely aren’t using the cheapest printer they can find.

“They're not just buying a simple printer off of Amazon and going out and printing a gun. They're buying a very high-end printer that's going to be able to handle an explosion,” said Randy Janes, owner of Wave of the Future 3D in Saskatoon.

“It's pretty crucial that it doesn't blow up on you when you're making these parts.”

But technology is changing, and 3D printing is getting easier for the average person to dabble in, Mendelson said. And criminals are always looking for workarounds.

“As long as you have the sort of technological smarts to be able to put these things together with the software, with the consumables that go into these 3D printers, we will probably see more of this, unfortunately, as we move down the road,” Mendelson said.

In June 2023, police seized 440 ghost guns and more than 50 3D printers in a cross-agency investigation that involved more than 20 police forces.

Officers carried out 64 raids in Quebec, Ontario, Alberta, British Columbia, New Brunswick, Nova Scotia, Manitoba and Saskatchewan that resulted in 45 arrests.

Ghost guns were unheard of ten years ago, Mendelson said. But he expects police will see more of them on the streets as Ottawa introduces new gun bans that make it harder for criminals to access guns.

“Criminals do their best to stay out of jail and they'll use technology to their advantage if, in fact, it will help them to access guns. Guns are not going to go away,” Mendelson said.