BOSTON (CBS) – An MBTA police officer is off the job after troubling accusations. Suffolk County District Attorney Rachael Rollins said she’s opening a criminal investigation into the actions of former MBTA Officer Nicholas Morrissey.

According to a Boston Globe report Monday, surveillance video shows the officer dragging a Black passenger off a bus at the Forest Hills train station on April 28, kneeling on the man’s back, and shoving his face into the ground. Rollins said the 63-year-old passenger was homeless and intoxicated, and is known to MBTA police.

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The Forest Hills MBTA station. (WBZ-TV)

The passenger was not seriously hurt. Morrissey filed a report saying that the man lost his balance while trying to spit on him, but Rollins said “the report is not consistent with video of the interaction.”

“Although it is unusual for my office to comment on ongoing investigations, the behaviors of law enforcement personnel must be held to a higher standard and require transparency,” Rollins said in a statement.

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Morrissey resigned on May 29 instead of facing termination proceedings. His supervisor is on administrative leave.

MBTA General Manager Steve Poftak sent this statement to WBZ-TV Monday:

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“The alleged events, as described, are contrary to the core values and mission of the MBTA and its police department. Transit Police officers receive specialized training in de-escalation techniques and are expected to treat riders with dignity and respect at all times. We take this matter very seriously. The Transit Police Department’s Command Staff is conferring with the Suffolk County District Attorney’s office and a thorough investigation is underway.”