Photo courtesy of the MBTA

Suffolk County District Attorney Rachael Rollins said Thursday that her office would open an investigation into whether the MBTA bore any criminal responsibility for the Green Line trolley crash last summer that injured 27 riders.

Rollins, who plans to leave the office on Monday when she is sworn in as the next U.S. attorney for Massachusetts, said the investigation will focus on whether the transit agency failed to address the behavior of a trolley driver with a “reputation for speeding and history of violations.”

“There is perhaps no single state agency that impacts the daily lives of the millions of people who live and work in the greater Boston area more than the T,” Rollins said in a statement announcing the probe. “Therefore, it is imperative that if we see a continued lack of oversight or negligence at the MBTA that it is exposed and corrected.”

The Green Line crash occurred last July when a trolley operated by Owen Turner slammed into another train from beyond. National Transportation Safety Board investigators later determined that Turner’s train accelerated before the crash, and Turner was charged with negligence of a person having care of public conveyance and gross negligence in management of a train.

Rollins said Turner’s colleagues and supervisors had been aware of his pattern of reckless behavior but failed to take action.

“When an employer willfully turns a blind eye to one of their employee’s dangerous and reckless actions, they become complicit in behavior. When those employee’s actions rise to the level of criminal conduct, there are circumstances where an employer can and should also be held criminally responsible for the acts of an employee,” Rollins said.

With Rollins set to leave the district attorney’s office Monday, the investigation will fall into the lap of Kevin Hayden, the chair of the Sex Offender Registry Board, who was tapped by Gov. Charlie Baker on Thursday to serve as district attorney until a new prosecutor can be sworn in after the November elections.

Rollins also said her office had opened a perjury investigation into former Boston Police Detective John Brazil regarding his testimony in two murder trials.