Empty frames where stolen paintings once hung at the Isabella Stewart Gardner Museum. Image: Getty

In 1990, thieves stole paintings worth $500 million from the Isabella Stewart Gardner Museum in Boston. The heist remains unsolved, but officials have repeatedly questioned and searched the Connecticut home of “Bobby the Cook” Gentile, a reputed mobster who is currently serving time on unrelated charges in federal prison. This week, the feds were back at Bobby’s house again.

The Gardner heist is one of the great American mysteries of the contemporary era. In 1990, two men dressed as Boston police officers entered the museum early one morning, telling the guard on duty they were responding to a call. They then handcuffed that guard and one other in the museum’s basement and left with 13 works, including three Rembrandts, a Manet, and five works by Degas.

The FBI named Gentile, who is serving a 2.5-year sentence for guns and weapons charges, as a person of interest in the case in 2014. He has denied knowledge of the paintings, and his lawyer claims prosecutors are using the crimes for which he was convicted to pressure him into producing the stolen art.

ABC News reports that FBI agents executed a search on Gentile’s home yesterday, the third time they have done so. A bureau spokesman confirmed the raid to ABC, but did not say whether it was related to the Gardner heist. A. Ryan McGuigan, Gentile’s lawyer, told the Boston Globe that agents were digging within 10 feet of the Gentile’s ranch house and searching near the chimney.

McGuigan told ABC that his client was unconcerned with the raid. “He laughed and he couldn’t believe...that they were at his house again,” he said. “And he said, this is a quote, ‘They ain’t gonna find nuttin.’”