The motorcyclist, identified as 38-year-old William Westmoreland, was taken into custody at a University Village motel Tuesday afternoon, Seattle police said.
Westmoreland's arrest was a big relief to the family who faced him down in Everett.
"We had a guardian angel looking out for us," said Thomas McPherson.
McPherson has been through a roller coaster of emotions, and so has his wife and three kids. First came the the violent crash -- a man on a motorcycle weaving through traffic at 80 mph right past them. He hit a car near 112th Street SE and his bike repeatedly rolled. McPherson said the biker was thrown 50 feet.
"My first thought was he's probably dead," McPherson said.
McPherson rushed to help him, but the biker refused. Turns out, he was wanted by police and the motorcycle he wrecked was stolen.
William Westmoreland was desperate to get away.
"I saw that he had climbed into our car in the driver seat and my wife was fighting with him as he was reaching for the ignition and steering wheel," McPherson said. "And she was saying 'No, no!' "
Other drivers stopped to help and pulled Westmoreland out of McPherson's car with his wife and three kids inside.
"There is no doubt had I left them in there he would have taken the car with my kids," he said. "They were in back seat, terrified."
Westmoreland ran off across the freeway and up a steep embankment. Thomas McPherson chased him up and over a 6-foot chain link fence, right into a neighboring apartment complex where police say Westmoreland stole another car and made a near-24 hour getaway.
"It had gone from trying to be a Good Samaritan to this person is a danger not only to himself but others," McPherson said.
The McPhersons say it's still surreal, but they're thankful for that guardian angel.
"Afterward we took the positive from it -- we're all OK," McPherson said.
Westmoreland was taken to Harborview after his arrest to be treated for injuries sustained in Monday's crash and will be booked into the Snohomish County Jail when fit for release, police said.