A memorial service for Tom Osmers at the Chilmark Community Center on Saturday ended with the arrest of well-known Menemsha fisherman Karsten D. Larsen, amid allegations that he groped a 15-year-old girl and punched a teenage boy.

Mr. Larsen, 43, of Flanders Lane, Menemsha, was charged with three counts of threat to commit a crime, two charges of assault and battery and one count of indecent assault and battery on a person 14 or over. During his arraignment on Monday a plea of not guilty was entered on his behalf, and he was released on $1,000 bail.

A group of teenagers attending the memorial service walked over to the police station at about 9:20 p.m. to report the incident.

The girl told police the man wrapped his arms around her neck and slid his hands down her shirt. The teens told police the man punched one of them in the chest and wrestled another to the floor when he tried to intervene.

Officer Jeffrey Day went with the teens to the Community Center, where they found a full parking lot, a band playing and over 100 people inside. One of the teens identified Mr. Larsen near the main entrance.

He was taken to the police station for questioning, and was later charged and arraigned.

The memorial service for Mr. Osmers on Saturday night was sponsored by WVVY, a nonprofit public radio station.