The Transit Police Department is looking for a man it says got on the Red Line at Ashmont around 10:50 a.m. on April 21, took off his pants and underwear and proceeded to "commit a lewd act."

Police add "this was done in full view of other passengers present" and say he apparently got off the train at Savin Hill - after getting dressed again.

If either end of the guy looks familiar, contact detectives at 617-222-1050 or send an anonymous text tip to 873873.