OAKLAND (CBS SF) — A man accused of viciously attacking a pair of Oakland sisters on a BART platform with a knife, killing one and stabbing the other, was in a Santa Rita jail cell Tuesday as authorities tried it unravel the motive behind the crime.

The Alameda County Sheriff’s Office confirmed to KPIX 5 that John Lee Cowell has a litany of arrests on his record from when he turned 18 to present day. Those arrests include vandalism, burglary, theft, trespassing, weapon charges, assault with a deadly weapon, stealing a vehicle, shooting into a dwelling, felony assaults and various drug charges.

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Cowell had been released from state prison a few months ago and was on parole at the time of his alleged crime. He was being held without bail on first degree murder and other charges.

“We don’t have a motive at this time,” said BART police chief Carlos Rojas during a Monday news conference.

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Nia Wilson and her two sisters were traveling on BART Sunday night when they stopped to help a woman struggling with a stroller exit a train. It was at that moment that a man — identified as Cowell — pulled out a knife, slashed Nia across the neck and stabbed her sister, Latifa, before fleeing. Nia’s wound proved to be fatal while her sister was treated and released from a local hospital.

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The manhunt for Cowell intensified Monday with BART officials releasing photos from surveillance cameras.

According to a BART source, authorities received an anonymous citizen call saying the suspect was on an Antioch-bound train in the East Bay. Police stopped the train at Pleasant Hill station, where officers boarded and arrested Cowell without incident.

The viciousness of Sunday night’s stabbing still stuns veteran police officials.

“In my close to 30 years of police experience, it was probably one of the most vicious attacks that I’ve seen,” Rojas said.

When asked later to elaborate, Rojas came up with a stunning comparison.

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“To me,” Rojas said. “It (the attack on the sisters) is more reminiscent of a prison yard assault. Where you have an individual with a sharp object or a shank and they do their attacks so quickly that before anyone can realize or react the person takes off running.”