According to historian and metal-detector enthusiast Jim Bailey, the handful of 17th-century Arabic coins unearthed at sites across New England could be remnants of an infamous pirate’s last big score—or, to put it another way, money stolen from a ship full of religious pilgrims during a horrific mass murder at sea.

“It’s a new history of a nearly perfect crime,” Bailey told the Associated Press.

Bailey found a handful of Colonial-era coins and musket balls, along with a shoe buckle, buried beneath a fruit orchard in Middletown, Rhode Island in 2014. Amid the English and Colonial-issued coins, Bailey noticed something unusual: a coin as weathered and tarnished as the rest but engraved in Arabic. It turned out to be a Yemeni coin called a khamsiyat, minted in 1693.