Authorities are investigating how a convicted rapist was allowed to serve as a foster parent to as many as 50 children before his past was discovered.

State laws prohibit all convicted felons, particularly those convicted of sex crimes (search) or crimes of violence, from being foster parents (search) or adopting children, except in rare instances.

But Nicholas Chaney (search) told WWNY-TV in Watertown Tuesday that he may have cared for as many as 50 foster children since late 2001 and even adopted a child while living in upstate New York. Chaney said he listed his felony sex crime conviction on his foster parent application form when he signed up in November 2001.

According to authorities in Oregon and Washington state, Chaney was convicted in 1989 of two counts of third-degree rape. Chaney told the television station he had been convicted of having sex with a 16-year-old girl.

Brian Marchetti, a spokesman for the state's Office of Children and Family Services, said the agency began an investigation Wednesday into why the Jefferson County Social Services Department approved Chaney's foster parent application.

"We are treating this matter very seriously," he said. "Children's safety and well-being are always our top priority. Every child deserves to be protected from sexual predators."

Jefferson County Sheriff's deputies are also investigating whether Chaney broke New York law by not registering as a sex offender when he moved to the state, Lt. Michael Petersen said.

In the TV interview, Chaney said he had not known he was required to register in New York, but did so recently after he received a warrant for failing to.

Chaney, his wife, their three biological children and the adopted child have moved away from the Watertown area, the Watertown Daily Times reported Wednesday. A 17-year-old foster child was taken from their care last week, the TV station reported.

The family's whereabouts could not be ascertained Wednesday.

Watertown is about 70 miles north of Syracuse.