A former administrator at a Washington prep school, already facing criminal charges of engaging in sex acts with three students, was arrested again Tuesday after investigators said they had identified a fourth victim.

Robert Reinhardt, 44, who resigned in June as dean of students at The Gunnery, surrendered to state police and was arraigned in Litchfield Superior Court on charges of second-degree sexual assault and providing alcohol to a minor.

He was released after posting a $200,000 bond.

Mr. Reinhardt, who now lives in Pennsylvania, had been employed by the school since 1996 in a variety of capacities, including crew coach, science teacher and a recruiter before he was named dean three years ago. He left after the parents of one of his victims claimed Mr. Reinhardt had assaulted their son.

The ex-dean was already facing two counts of second-degree sexual assault, one count of fourth-degree sexual assault and two counts of illegal sexual contact with a person under the age of 16. Those incidents allegedly occurred between October 2007 and last June, police said.

He had been free on a combined $750,000 bond in those cases.

At the time of his arrest in August, state police said they believed there had been a fourth victim and that additional charges were possible.

Mr. Reinhardt hasn't yet formally pleaded to any of the charges but his attorney, William Dow, previously had said Mr. Reinhardt will plead innocent.

He is due back in court next Friday.