A man named Thomas Gavin could be one of the most prolific artifact thieves in American history, but there are no movies or books about him.

It was not until a few years ago that anyone had ever heard his name, NPR reported on Sunday.

“But Gavin had been on a tear in the ’60s and ’70s, hitting nearly a dozen museums on the East Coast. He mostly stole antique firearms and stashed them in his hideout — a cluttered, non-descript barn in rural Pennsylvania,” the outlet said.

His crime spree was so unknown that no one figured it out until 2018 when the man attempted to unload a rare, Revolutionary-era rifle to an antique dealer.

Initially, Kelly Kinzle did not realize what he was seeing.

“I looked at it and I said, ‘Well, this is a copy of a famous rifle,'” Kinzle explained. “I said, ‘This isn’t the original — has to be a copy.’ And he didn’t say anything, didn’t correct me, and I bought it literally for a copy of a famous gun.”

Once Kinzle took it home, he had a feeling about it and continued studying the gun.

“I took it apart and when I took it apart. It was period. It was correct. I went to a reference book — I had bought an old out-of-print book — and I flipped through it and I found a photograph of the gun,” Kinzle commented.

“And under the photograph, the caption was: ‘Stolen from the Valley Forge Historical Society in 1970,'” he added.

It turned out to be one of the only surviving rifles crafted by master gunsmith John Christian Oerter.

Video footage from 2019 showed the stolen rifle in a display case:

The copy Kinzle believed he purchased for $4,000 was accurately valued at $175,000.

The Federal Bureau of Investigation (FBI) was searching for the rifle, and when agents questioned Gavin about how he came to have it, all was revealed.

That happened in 2019, and the case has finally made it to the courts, resulting in a ruling.

However, it was not clear the number of items the 78-year-old Gavin allegedly stole.

“It’s been so long that a lot of the places he claimed to hit don’t exist anymore, or they don’t have a record of the thefts. And most of the statutes of limitations on the items he stole have expired,” the NPR report said.

Gavin recently pleaded guilty to a count of “disposal of an object of cultural heritage stolen from a museum,” the outlet added.

A judge considered the man’s age and health condition and sentenced him to a day in prison after decades of theft.

According to NPR, the rifle was put on display inside the Museum of the American Revolution in Philadelphia, where it was on loan from the Pennsylvania Society of Sons of the Revolution.