These 1984 file photos originally released by the FBI show James "Whitey" Bulger.
BOSTON (AP) - Federal prosecutors say a request by former Boston mobster James "Whitey" Bulger to remove his trial judge is "frivolous and unsubstantiated."
A motion they filed late Monday also calls "absurd" a claim by Bulger's attorney that the one-time FBI informant shouldn't be prosecuted on charges he participated in 19 murders because the government promised him immunity years ago.
Bulger's attorney J.W. Carney Jr. filed a motion last month to remove Judge Richard Stearns because he was a top federal prosecutor when Bulger is accused of committing crimes with impunity. Carney argued the judge would try to shield his former colleagues and couldn't be impartial.
Prosecutors say those arguments are baseless and should be dismissed without a hearing.
Bulger was captured in Santa Monica, Calif., last year after 16 years on the run. His trial is set for March.
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