The 48-year-old American citizen, who was living in Edmonton before he went missing, was located by police in Washington state on Thursday.
He was not arrested, because authorities in Alberta have not sought his extradition. But a top official with the U.S. Marshals in Seattle said a warrant for his arrest would be issued if Stanley had not registered as a sex offender in Washington by Tuesday.
Stanley has a history of offences involving children.
He was sentenced in 2006 for assault and unlawful confinement after luring two mentally impaired boys to an Edmonton apartment. One boy was 13, the other was nine.
In the late 1980s, he spent nine years in prison for the aggravated sexual assault of an 82-year-old Lethbridge, Alta., woman who was confined to a wheelchair.
A manhunt was launched Oct. 1 after Stanley left Edmonton, where he was serving a peace bond that required him to stay close to the city and stay away from children, among other conditions.
Police were made aware of Stanley's flight when he cut off his electronic monitoring bracelet in Lloydminster, on the Alberta-Saskatchewan boundary.
The charges Stanley is wanted on are not severe enough to justify asking American authorities to turn him over, according to Alberta's solicitor general.