OAKLAND, Calif. (AP) — The hunt for a man police say killed an 18-year-old woman in an unprovoked knife attack in the San Francisco Bay Area ended where it began: In a train station.

John Cowell, 27, a recently paroled robber with a violent history, was peacefully arrested on an Antioch-bound train Monday night about a dozen miles from the Oakland station where investigators believe he killed Nia Wilson and wounded her sister Sunday night.

“This is the first step to achieving justice for Nia and her family,” Bay Area Rapid Transit Police Chief Carlos Rojas said at a news conference.

A phone call from a BART rider led police to stop and search a Richmond-bound train at the MacArthur Station in Oakland but Cowell wasn’t aboard, Rojas said.

“About 10 minutes later after we got the call, another patron told us the subject got on an Antioch-bound train,” Rojas said.

That train was stopped at the Pleasant Hill station in Walnut Park, northeast of Oakland. Cowell was on board and was arrested without incident. It wasn’t immediately known if Cowell had a lawyer.

Asked how a wanted man could have gotten back into the BART system, Rojas said he didn’t immediately know but said the public transportation system is “porous” and large.

Rojas said police officers were on duty at the MacArthur station where the attack took place but wasn’t sure it could have been prevented because of the suddenness of the unprovoked and possibly random attack.