MBTA Transit Police are asking for the public’s help in identifying a man who they said took off his pants on the Red Line and committed a “lewd act” in front of passengers.

The suspect boarded a Red Line train at Ashmont Station around 10:50 a.m. on  Thursday, April 21st.  He took a seat, removed his pants and underwear, and ” laid down and began to commit a lewd act,” according to police.

“This was done in full view of other passengers present,” police reported.

The MBTA has released photos of the man in question. Pictures show a dark-skinned adult with facial hair, wearing black sweatpants, a grey hooded sweatshirt, a black beanie, and grey New Balance sneakers. The hood of his sweatshirt said “RARE” in block letters.

Another photo shows the man’s bare legs as he was apparently caught in the act, with his New Balance sneakers on the floor beside him.

Transit police are calling it an “open and gross investigation.”

Under Massachusetts state law, lewd behavior falls under “disorderly conduct,” a possible misdemeanor charge. The Commonwealth also considers indecent exposure a misdemeanor, unless it is an aggravated act that rises to the level of “open and gross lewdness.”

Anyone with further information about the individual depicted in the photos is urged to reach out with a phone call or text message to the Transit Police Criminal Investigations Unit at 617-222-1050. Transit police will respect the wishes of those who want to remain anonymous.