Paul F. Ware, the lawyer who led the investigation into patron­age in the Probation Depart­ment, is accusing the state’s top administrative judge of abusing his powers in a homi­cide case in which Ware is the defense attorney, deliberately delaying rulings that might give Louis R. Costa a new trial.

Ware will ask a justice of the Supreme Judicial Court next month to order Chief Justice Robert A. Mulligan to remove himself from Costa’s case and allow another judge to determine whether Costa deserves a new trial in the 1986 slayings of two men in the North End. Other­wise, Ware warns in his request for a hearing before the state’s top court, Mulligan could keep Costa in a “legal deep freeze” indefinitely, ­despite new evidence that could exonerate him.