MERRIMACK – A juvenile girl and her mother sat down with officers at the Merrimack Police Department on March 21 to report a sexual assault they say occurred in December.

Police investigated the complaint and on Friday arrested a local man for sexual assault.

Thomas Costa, 20, of 135 Middlesex Road, was charged with one count of aggravated felonious sexual assault and one count of misdemeanor sexual assault, police said.

Costa was held over the weekend on $10,000 cash bail and arraigned Monday morning in Merrimack district court, police said.

– PATRICK MEIGHAN