Police in several provinces have been searching for Stanley since he cut off his electronic monitoring bracelet on Oct. 1 in Lloydminster, Alta.
A vehicle belonging to the 48-year-old Edmonton man was found in west Lethbridge on Monday.
There have also been numerous unconfirmed sightings of Stanley, police said.
He has a lengthy history of assaults and sexual assaults, and is considered a high risk to reoffend.
Stanley has a history of taking children from playgrounds. In 2006, he was sentenced to time behind bars for assault and unlawful confinement after luring two boys with mental impairments — who were age nine and 13 — to an Edmonton apartment.
He also spent nine years in prison for the aggravated sexual assault of an 82-year-old Lethbridge woman who was confined to a wheelchair.
Schools have been put on alert and wanted posters placed around Lethbridge.
Stanley is described as five feet nine inches tall, 190 pounds, with black hair and brown eyes.
He was released from prison in April 2011 after completing a 32-month sentence for assault and forcible confinement.
One of the conditions of his release was that he wear an electronic monitoring bracelet.