J.W. Carney Jr. also said Monday he has asked the trial judge to recuse himself because he was a top federal prosecutor.
Bulger, a former top-echelon FBI informant, is accused of participating in 19 murders. His former FBI handler John Connolly was convicted of protecting Bulger from prosecution and tipping him off before he was indicted in 1995.
A magistrate judge on Monday delayed Bulger's trial until March 4, 2013. Carney asked for a one-year delay from this November to November 2013 to allow him more time to prepare.
The 82-year-old Bulger was caught last June in California after 16 years on the run.