taking the stand and swearing to tell the whole truth were a former massachusetts governor and u.s. attorney ( william weld ) ; a sitting superior court judge and former protege of prosecutor jeremiah t. o'sullivan ( diane kottmyer ) ; the three fbi supervisors who ran the boston office during the bulger years ( lawrence sarhatt , james greenleaf , and james ahearn ) ; and a long line of federal drug agents , other fbi supervisors , and many of the fbi agents who 'd worked alongside connolly ( nick gianturco , ed quinn , and john newton ) .