BELFAST, Maine — A longtime Belfast foster parent has been charged with gross sexual assault against a 9-year-old foster child.

Lawrence D. Oxton, 71, was arraigned on two sexual abuse charges Friday afternoon at Belfast District Court.

Belfast Police Chief Mike McFadden said the department began investigating Oxton in mid-March, after receiving a referral from the Maine Department of Health and Human Services. The child, who was no longer living at Oxton’s Pitcher Road home, told another caregiver about inappropriate contact that allegedly had happened with Oxton, the chief said.

Detective Sgt. Bryan Cunningham and a DHHS caseworker interviewed Oxton at that time, but no charges were brought against him then because there was insufficient evidence or cause, McFadden said. Oxton denied at that time that inappropriate contact had occurred.

But at 6 p.m. Wednesday, Oxton went to the Belfast Police Department and told the sergeant on duty that he was there to turn himself in, McFadden said. There were no warrants or charges pending at that time.

“I came in to interview Mr. Oxton with regard to why he was turning himself in,” McFadden said. “I will say that as a result of that interview, we gained the probable cause necessary to make an arrest.”

Oxton, who has been a foster parent for 15 years, was charged with gross sexual assault, a Class A felony, and unlawful sexual contact, a Class B felony. A Class A felony carries a penalty of as much as 30 years imprisonment and $50,000 fine, while a Class B felony has a penalty of up to 10 years in prison and a fine of up to $20,000.

McFadden said police would be working closely with DHHS to investigate the possibility of similar incidents and that “we believe the investigation may result in further charges.”

David Sorensen, DHHS spokesman, confirmed Friday that “this licensed foster family is under investigation relating to abuse allegations.”

Oxton has been taken to Two Bridges Regional Jail in Wiscasset.

A jail official in Belfast said Friday afternoon that bail had been set but that he hadn’t yet seen the paperwork that would give the financial details.

Oxton was arraigned via video conference from the Wiscasset facility.