WORCESTER, Mass. — A Massachusetts state police trooper has been relieved of duty after being indicted on sexual assault charges.

The Worcester District Attorney’s office said Friday that 38-year-old Jason Willard of Auburn has been indicted on three counts of indecent assault and battery and two counts of open and gross lewdness. The indictments allege Willard assaulted an 18-year-old girl four years ago.

State police spokesman David Procopio said the alleged incidents took place while Willard was off-duty.

Procopio said Willard joined the state police in 2002 and is assigned to the Sturbridge Barracks. A duty status hearing is scheduled for Monday.

Willard is to be arraigned Sept. 21 in Worcester Superior Court.

He could not be reached by telephone Friday for comment. It’s not immediately known who is representing him.