A Watertown resident who was sentenced to state prison in 1991 after he kidnapped two children and sodomized one was charged Thursday by St. Lawrence County sheriff's deputies with failing to inform the state sex offender registry that he had moved to Watertown.

William J. Dempsey Jr., 49, formerly of 123 County Route 4, Heuvelton, was charged with a misdemeanor charge of failing to register as a sex offender. He was arraigned in Oswegatchie Town Court and was released pending further court action.

A Level 3 sex offender, Dempsey had been living in Watertown for the past several months and failed to register the address change with the state Sex Offender Registry, deputies said. He listed 249 Coffeen St., as his address in March when charged by Watertown police with cruelty to animals.

Dempsey was classified as a Level 3 sex offender as a result of his 1991 conviction for first-degree sodomy. Level 3 offenders are considered the greatest risk to repeat their crimes and are required to report all changes of address.

Dempsey pleaded guilty in St. Lawrence County Court in satisfaction of charges stemming from an August 1990 incident in which he abducted an 11-year-old boy and his 6-year-old sister from the parking lot of an Ogdensburg area convenience store. Their father had left the children in the family car while he was in the store.

Located by state police after a two hour search, Dempsey later admitted sodomizing the boy. The girl was not molested, police said.

He was sentenced in May 1991 to eight to 16 years in prison and was released on parole on May 16, 2006.