Seattle police received several reports that a man was yelling in an alley in West Seattle just before 6 a.m. Tuesday, said Det. Mark Jamieson.
One caller told officers that when he had asked the man to quiet down, the man had threatened to assault him, Jamieson said.
Police arriving on the scene found Stanley, who became combative with officers and claimed he had a knife.
After finding a small knife on Stanley, who appeared intoxicated, officers booked him into the King County Jail on a misdemeanour charge of harassment.
After Stanley cut off his electronic monitoring bracelet and fled, Canadian officials issued a public alert describing him as an untreated, violent offender who posed a significant risk.
Unconfirmed sightings of the Edmonton man led schools in several west-central Saskatchewan communities to lock their doors and keep children inside.
Stanley, a U.S. citizen, crossed the border and was located in the Seattle area last week. Authorities asked him to register as a sex offender after Canadian officials decided not to seek extradition.
His address online was listed as an intersection just a block away from Pike Place Market, a scenic destination for both tourists and locals that is also near a preschool.