This past Friday, six Pennsylvania museums were reunited with a variety of firearms that had been stolen by a man during heists that sometimes would go unnoticed for several years, writes Ximena Conde for The Philadelphia Inquirer.

Thomas Gavin, the now 78-year-old man behind the thefts, admitted to targeting dozens of museums all along the East Coast during the 1960s and ‘70s.

At the time, these institutions that housed these artifacts were often almost entirely volunteer-led and thus were much easier for Gavin to infiltrate.

“Security, of course, was not what it is today,” said Scott Stephenson, president of the Museum of the American Revolution. “Generally, there weren’t the sort of alarmed cases and that sort of thing, and so that made it a lot easier for a perpetrator to come in and steal objects.”

With few security provisions in place, such as the use of a glass display case that could easily be pried open with the right tools, a thief like Gavin found little difficulty during his heists.

Thomas Gavin had stolen two English-made pocket pistols, as well as French military pistols dating to the American Revolution-era from the museum’s predecessor, the Valley Forge Historical Society.

Nowadays, security systems at museums are much stronger.

Although they won’t share all their secrets, it’s common protocol not to allow backpacks or puffy coats in certain collection rooms, and staff is always watching camera displays to prevent theft.

Although many museum leaders feel confident they can prevent future thefts, they still have logs with missing artifacts that could be anywhere. They hope repatriation ceremonies will encourage antiques dealers and collectors to look closer at their items.

“People who are purchasing antiques or something, maybe will inquire a little bit about the provenance of an object and who the previous owners were and maybe further things will come out of the woodwork,” said Stephenson.

Read more about the return of the firearms stolen from Thomas Gavin in The Philadelphia Inquirer.