BOSTON (AP) — A lawyer for James "Whitey" Bulger continues to challenge a claim by prosecutors that Bulger was a top-echelon FBI informant who secretly ratted on the Italian Mafia and other criminals.

Attorney Hank Brennan kept up an aggressive cross-examination Wednesday of an official with the Justice Department's Office of the Inspector General. Prosecutors called the official to testify in Bulger's racketeering trial to introduce Bulger's FBI informant file.

Bulger is accused of playing a role in 19 murders in the 1970s and `80s while allegedly running the Winter Hill Gang.

The 83-year-old has pleaded not guilty and his lawyers have strongly denied that he was an FBI informant.

The defense contends that former FBI Agent John Connolly fabricated Bulger's FBI file in an attempt to cover up his own corrupt behavior.

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