The offender, Gordon Michael Strauss, told the station he hadn't been treated fairly. He was at a downtown police precinct Thursday to take his name off the list of homeless sex offenders living in Portland.
Police Officer Bridget Sickon says Strauss is headed back to Seattle where he has family and friends.
KATU reports Strauss was convicted of four rapes since the 1980s and spent a decade in prison. He's known for snatching teenage girls off the streets.
He spent 14 years at an institution in Washington that treats sexual psychopaths, but he wasn't on supervision when he came to Portland last week.
He'd most recently listed his address as "homeless" living in the area of Northwest 9th and Lovejoy in the Pearl District of Portland.
"You people runned me out of the state, you should be proud of yourself," he told KATU News after he deregistered. He said he hadn't been treated fairly.
A computer query by Portland Police Bureau Officer Bridget Sickon returned a list several pages long of sex offenders like Strauss who don't have a permanent address.
Sickon said the rules in Oregon for homeless sex offenders are more lenient than in neighboring states, making it a draw for rapists like Strauss.
"And which ones are the other type, like Mr. Strauss, who's using his right to register as homeless in Oregon as a way to circumvent being monitored," she said.
As for Strauss, he told KATU News he's dying from lung disease.
"I can't walk fast, and I can't deal with this," he said. "So just do me a favor and let me go."
Strauss' lung disease hasn't been confirmed, but he was observed lighting a cigarette while talking about his condition.