A Mattapan man with a history as a high-risk sex offender was arrested at Ashmont station this morning after an MBTA inspector saw him masturbating as he followed a woman walking toward a Red Line train, the MBTA says.

According to a police report, Jerome Reed, 49, got off the Mattapan trolley in Ashmont around 9:30 a.m. with his erect penis hanging out. He began following a female passenger, masturbating as he walked. The T inspector who observed this was "absolutely disgusted" by the "shocking and alarming" behavior, police say.

Reed is a "Level 3" sex offender, which means they have been convicted of sex crimes in the past and are prone to committing more.

Innocent, etc.