WASHINGTON — Federal prosecutors sidestepped some Justice Department rules when they seized the phone records of reporters as part of media leak investigations during the Trump administration, according to a new watchdog report being released as the aggressive practice of hunting for journalists’ sources could again be resurrected.

A two-year investigation by the agency found patterns of “outrageous” conduct by the police in Worcester, Mass., including excessive use of force and sexual contact between undercover officers and women suspected of prostitution.