The hunt for one of the world's most wanted men has brought FBI agents to London, where they are seeking the advice of detectives at Scotland Yard.
James J Bulger is being hunted in connection with 18 counts of murder and various racketeering and drugs offences and has a $1m price on his head.
Mr Bulger vanished in 1994 and appears directly below Osama Bin Laden on the FBI's top 10 most-wanted website.
According to the FBI, he was captured on video this year in Sicily.
Mr Bulger is accused of leading an Irish-American crime syndicate in Boston, Massachusetts, in the 1970s and 80s that controlled drugs, protection and extortion.
Nick-named 'Whitey', he disappeared shortly before being arrested on racketeering charges.
He was later identified as a long-term FBI informant who had turned in rival gangsters.
The FBI believes video footage at a resort in Sicily shows him and his long-term dental hygienist girlfriend.
According to the US authorities, Mr Bulger has a violent temper and always carries a knife.
FBI agents have previously visited London following a reported sighting in Piccadilly five years ago.
A businessman said he saw Mr Bulger near the Meridian Hotel on 10 September 2002, and had also seen him in the hotel's gym in 1994.