GRAND RAPIDS, Mich. (WOOD) — The man who shot and killed a Wyoming motel guard used what’s called a ghost gun, a nearly untraceable weapon.

The homicide at the Grand Rapids Inn in Wyoming on Nov. 1 killed security guard, father and coach John Cain Jr., 38. Shooter Jacob Grygorzyk recorded the shooting and later turned the gun on himself, police say.

“A ghost gun has been put together by pieces, parts that can be ordered and you put together. It’s not produced by a manufacturer,” Wyoming Department of Public Safety Lt. Brian Look said.

That means there’s no serial number or manufacturer name. The guns don’t even list a caliber. As a result, no one knows who they are linked to.

The guns are easy to buy. A quick online search brings up dozens of sites selling kits for under $500 or cheaper. Ghost guns have been around since the 1990s but didn’t take off until about 2009.

The pieces themselves are legal, but when put together, they become an illegal firearm.

In Michigan, all guns must have a registered serial number. Ghost guns allow people to get a gun without one.

Once these firearms are sold on the street, tracing them becomes nearly impossible.

“We do not know where Jacob Grygorzyk got the gun at. We know that it ended at a tragic unnecessary event,” Look said.

Wyoming police say this is their first homicide involving a ghost gun. but it’s a growing trend nationally. President Joe Biden is working with Congress to ban ghost guns.

Federal and state law prohibit anyone from owning a gun if they have been involuntarily hospitalized. Court documents show a request to have Grygorzyk involuntarily hospitalized in 2020 because he was a danger to himself. He agreed to get treatment at that time, but it’s unclear whether he was ever involuntary committed at another time.