A wheelchair-bound, 76-year-old Connecticut mobster pleaded guilty to weapons and prescription drug charges in a case that exposed him as possibly knowing about the 1990 Isabella Stewart Gardner Museum heist.

The largest art theft in history, which included 13 stolen masterworks worth half a billion dollars, is still unsolved. The FBI has indicated that the elderly mobster Robert Gentile might be linked to the Boston museum theft.

Gentile's hearing at the U.S. District Court in Hartford was for illegally possessing and selling prescription drugs and illegally possessing guns, silencers and ammunition as a convicted felon.

His connection to the Gardner heist was not mentioned until after the hearing when his lawyer, A. Ryan McGuigan, said, "Unfortunately for the art world, he is the last, best hope of retrieving the paintings."

McGuigan says that Gentile does not know about the theft, but was acquainted with people who federal authorities believe were involved. Most of those people are now dead, according to Gentile.

"And now he's paying price for not knowing," says McGuigan of his client.

Gentile has cooperated with federal investigators in their attempt to find the stolen art and testified before a grand jury looking into the heist, his lawyer says.

A $5 million reward is offered for the return of the Gardner's artwork.