Updated

A reputed Connecticut mobster who authorities say is the last surviving person of interest in the largest art heist in U.S. history is expected to plead guilty to unrelated weapons charges.

Eighty-year-old Robert Gentile is scheduled to appear in federal court in Hartford on Thursday. Details of the plea agreement have not been released. The charges stem from numerous firearms and ammunition seized from Gentile's home in Manchester.

Prosecutors have said they believe Gentile has information about the still-unsolved 1990 heist at the Isabella Stewart Gardner Museum in Boston. Thieves stole an estimated $500 million worth of artwork, including works by Rembrandt and Edouard Manet.

Gentile has denied knowing anything about the heist or the paintings.

His lawyer and a U.S. attorney's office spokesman declined to comment Wednesday.