The government has given them thousands of pages of documents and other materials that may be used during Bulger's trial.
The former leader of Boston's notorious Winter Hill Gang was arrested in Santa Monica in June after 16 years on the lamb.
He was living in a rented apartment with his longtime girlfriend, Catherine Greig. Bulger, a longtime FBI informant, was wanted in connection with 19 murders. He fled Boston just before he was indicted in early 1995.
Meantime, there's another development in the Bulger case. Keith Messina, a Las Vegas man who tried to claim the $2 million reward for Bulger's arrest, said the FBI has denied his claim and instead paid the money to another tipster who crossed paths with Bulger in Southern California.
The FBI has not confirmed that the reward was paid.
Messina said he was in Santa Monica with his wife and children when he saw a man who resembled Bulger standing by a pier, wearing shorts and reading a thick book.
He said that when a young couple walked by, Bulger appeared to notice the man's shirt, which had some kind of Boston insignia on it. Messina said they started talking about various places in Boston.
Messina said he then looked on the "America's Most Wanted" website, recognized the man he saw as Bulger and called staff members at the show to give them his tip. He said he later was told by the staff members that they had passed his tip along to the FBI.
The Associated Press contributed to this story