A Danbury man who has taught at a private Catholic girls' school in Greenwich for the past 17 years has been charged with sexual assaulting a minor, police said. Michael Maida, 44, surrendered to police on Tuesday. He is charged with second-degree sexual assault and risk of injury to a minor, according to police. The charges stem from an investigation into alleged contact between Maida and a student who was under the age of 16 at the time, police said. Maida teaches at Convent of the Sacred Heart day school in Greenwich. According to a statement from the school, the alleged incident took place in the fall of 2009 and the alleged victim is no longer a student.