RELATED: This is the moment the BART stabbing suspect was arrested
His first court date has been set for Thursday morning.
Cowell was arrested last night at the Pleasant Hill BART station. Police say he was not armed when they arrested him, and that an anonymous tip led to the arrest. A "925" tattoo on Cowell's neck helped the rider identify him.
They still don't know the motive behind the violent attack that killed 18-year-old Nia Wilson. Police say she and her sister were attacked from behind Sunday night at the MacArthur station in Oakland. They were both stabbed. Nia died from her injuries.
VIDEO: 'Remember Her' A tribute to Nia Wilson
A motive remains unclear.
No bail has been set. Cowell will be arraigned Thursday morning.
During a press conference Tuesday, BART police said the stations where the most violent crime occurred were the Richmond, MacArthur, Coliseum, Daly City and San Leandro stations. They encourage riders to stay vigilant, and to have the BART police dispatch number, or the BART Watch app on their smartphones.
Go here for full coverage on the stabbing at Oakland's MacArthur BART station that took the life of 18-year-old Nia Wilson.
CONTINUING COVERAGE ON DEADLY BART STABBING:
- What we know about deadly stabbing at Oakland's MacArthur BART station
- 'Remember Her' A tribute to Nia Wilson
- Here's how you can help the family of BART stabbing victim Nia Wilson
- Chilling dispatch call describes terrifying fatal MacArthur BART stabbing
- 'He was wiping off his knife': BART stabbing victim recalls horrific attack that killed sister
- Heartbroken father demands justice after daughter stabbed at BART station
- 'Stand down': BART stabbing victim's godfather makes plea to black community
- TIPS: How to stay safe on BART
- Bart releases info on pair of homicides