King County Sheriff's Sgt. Cindi West confirmed Friday that Michael Sean Stanley had registered as a sex offender as required by police.
Authorities located the 48-year-old in downtown Seattle on Thursday and said he would be arrested if he failed to register within three days.
Stanley has a long history of sexual offences against women and children and had been missing since Oct. 1, when he left Edmonton and cut off his electronic-monitoring bracelet in Lloydminster, on the Alberta-Saskatchewan boundary.
Edmonton police said they warned U.S. counterparts that he might try to cross the border, but U.S. officials allowed him in after determining he was an American citizen and not the subject of an extraditable arrest warrant.
Last weekend, Alberta Justice announced it would not seek Stanley's extradition to Canada because the breach of recognizance, mischief and driving charges he faces north of the border don't involve violence.
Alberta Justice acknowledged Stanley's violent record, but said the charges he is currently facing "do not typically warrant engaging the extradition process." The department said it was prepared to prosecute him if he tried to return to Canada.
At least one Canadian extradition expert has sided with leaving Stanley in the U.S., saying extradition would be costly and any punishment under the charges he faces would be minimal.
But Alberta's official Opposition Wildrose party has called the government's actions "morally reprehensible" and demanded that Justice Minister Jonathan Denis try to get Stanley back.
Stanley's criminal record in Canada dates back to 1987.
The 48-year-old last received a 32-month prison term for assault and forcible confinement involving two mentally challenged boys. Parole board records say he lured the boys into a washroom, blew crack smoke in their faces and then sexually assaulted them.
Parole records also detail the sexual assault of an elderly woman and outline charges that he exposed himself to kids.
The board determined that Stanley posed a risk to reoffend and kept him behind bars until his warrant expiry date, the final day of his sentence, in 2011.
He was being monitored by police under a peace bond with conditions, including one ordering him to stay away from children.