Robert Garrison of Niagara Falls admitted in Niagara County Court on Wednesday to failing to register as a sex offender.
Garrison, 54, was convicted in November 1989 of raping a 12-year-old girl in Niagara Falls while armed with a knife. He was sentenced to 2-1/3 to 7 years in state prison and was required to register as a Level 2 sex offender for life.
But he did not register when he moved from Ontario Street, Lockport, to Niagara Falls.
Garrison faces up to four years in prison when he is sentenced before Judge Sara Sheldon on Oct. 2.