A retired Boston jeweler says he may have briefly had his hands on an item stolen in the infamous Isabella Stewart Gardner Museum heist, the biggest art theft in history and one that remains unsolved three decades later. In an interview with the Boston Globe, Paul Calantropo, a fine-art appraiser, said a friend named Bobby Donati asked him to appraise a bronze eagle finial in 1990, but he told him the piece wouldn’t fetch any money because it was clearly stolen in the heist a few weeks earlier. The thieves, disguised as police officers, had made off with about $500 million worth of fine art masterpieces.

“Jesus, Bobby, why didn’t you steal the Mona Lisa?” Calantropo said he quipped to Donati at the time. According to the Globe, Donati was found dead just over a year after that encounter, with investigators at the time noting his connections to a reputed mobster. No arrests were ever made in the notorious heist, but investigators had eyed the local mob as a possible culprit. Calantropo said he was afraid to come forward about the eagle finial for years, but he broke his silence now after revealing the information to the FBI.