A Level 3 sex offender is facing a charge that he groped a woman on a Green Line train in December, the latest in a string of similar cases against him, prosecutors said.
Dane Mullin, 27, of Salem pleaded not guilty Tuesday in Boston Municipal Court to a charge of indecent assault and battery.
He allegedly assaulted the woman just before 7 a.m. on Dec. 17 on an E Line train between Haymarket and Government Center, Suffolk District Attorney Daniel F. Conley’s office said Wednesday.
The judge ordered Mullin held without bail on a probation violation and on open warrants from Salem District Court for failing to register as a sex offender, prosecutors said.
MBTA Transit Police arrested Mullin in February and charged him in connection with the December assault, after questioning him about the theft of a cellphone from a passenger on a Green Line train, Transit Police said.
The arrest in connection with the December assault violated the terms of Mullin’s probation on a past conviction for assaulting two women in separate incidents at North Station in March 2011, prosecutors said. Mullin was sentenced to serve 18 months in a house of correction in that case.
Mullin has four other convictions for indecent assault and battery dating back to 2007, according to the state Sex Offender Registry.
He is slated to return to court June 6.Lauren Dezenski can be reached at lauren.dezenski@
globe.com. Follow her on