(CNN) -- Law enforcement agents began searching the Connecticut home of an alleged mobster on Thursday. But the suspect's attorney says authorities are actually hunting for hundreds of millions of dollars in stolen art that went missing from a Boston museum more than 20 years ago.
Ryan McGuigan, an attorney for Robert Gentile, a 76-year-old Connecticut man facing federal drug charges and illegal firearms possession, said it's the second time authorities have scoured the man's home.
"Pursuant to the search warrant, they are looking for firearms," said McGuigan. "But they're not really looking for firearms. They're looking for $500 million in (art stolen) from the Isabella Stewart Gardner Museum on March 18, 1990."
Pieces by Rembrandt and Degas were among the artworks stolen in the notorious heist.
The U.S. Attorney's office declined to comment on the apparent search.
Manchester Police spokesman Chris Davis said law enforcement agents were at the scene and that the FBI had been requested.
In an earlier statement, the museum said it "does not have any comments about the Robert Gentile case in Connecticut."
"The Museum continues to offer a $5 million reward for information leading to the recovery of the artworks in good condition," the statement read. "Anyone with information about the theft, the location of the stolen artworks, and/or the investigation, should contact the Gardner Museum."
Hours after St. Patrick's Day festivities wrapped up in Boston on March 18, 1990, two men dressed as police officers knocked on the museum's side security entrance.
Upon entering, the intruders handcuffed the security guards, bound them with duct tape and left them in the basement, authorities said at the time.
In less than 90 minutes, the bandits went through the museum's Dutch Room on the second floor and stole three Rembrandts, including the Dutch artist's only seascape, "Storm on the Sea of Galilee," along with Vermeer's "The Concert," five Degas drawings and other items, according to the museum's website.
The thieves also apparently tried to steal a fourth Rembrandt but were unsuccessful, the FBI reported at the time. The agency said that their early investigation led authorities to examine several different groups, including members of Boston's organized crime gangs and the Irish Republican Army.
CNN's Jake Carpenter contributed to this report.