"Whether or not the defendant was granted immunity is at the core of this case," the defense wrote in a court filing Friday.
Carney recently stunned prosecutors when he said Bulger was never an FBI informant. In documents filed in court Friday, prosecutors said the claim that Bulger was not an FBI informant, but still had immunity is "both strange and unsubstantiated."
In their statement Monday, Bulger's lawyers said Bulger is prepared to testify "how and why he received immunity" from O'Sullivan "for past and ongoing crimes."
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