BOSTON -- Defense attorneys Tuesday suggested that an admitted mob hit man testified against a former FBI agent out of revenge.

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NewsCenter 5's David Boeri reported that John Martorano testified Monday that information from retired FBI Agent John Connolly led to the mob murders of three men in the 1980s.

The defense tried to prove Tuesday that that Martorano was testifying to get back at a mob informant.

Martorano said Monday that Connolly was involved in an effort to protect mobster James "Whitey" Bulger at the request of his brother, then Senate President William Bulger. William Bulger has denied that he asked Connolly to keep his brother out of trouble.

Martorano admitted under defense questioning that he never spoke to Connolly directly. He said that he got his information about Connolly from Whitey Bulger and mobster Stephen "The Rifleman" Flemmi.

Martorano said that Whitey Bulger and Flemmi were the ones who told him that Connolly betrayed the identity of three FBI informants, who later were killed.

Flemmi was also informing for the FBI, and the defense suggested that Martorano was testifying against Connolly in an effort to get back at him and Flemmi. Martorano said that when he found out that Flemmi was a snitch, he was disgusted, furious and upset.

Martorano admitted that he told another inmate that he wanted to kill Flemmi.

Later Tuesday, admitted mob enforcer Kevin Weeks described the 1982 murder of Brian Halloran, an FBI informant. Prosecutors said that Connolly tipped off Whitey Bulger that Halloran was talking to the FBI.

Weeks said that he was the lookout in the Halloran killing.