The man accused of killing Nia Wilson at a BART station in Oakland, California last month could face the death penalty after his murder charge was upgraded on Wednesday.

An Alameda County District added a special circumstance count of “lying in wait” for 27-year-old John Lee Cowell, according to East Bay Times.

Cowell is accused of stabbing and killing 18-year-old Wilson on the evening of July 22 while she and her sister waited at a BART station. He was arrested the following day after police searched for him for almost 24 hours.

On top of qualifying for the death penalty, Cowell could receive life in prison without parole if he’s convicted for Wilson’s death, per the report.

“I’m deeply concerned that they’re now seeking death possibly for someone that has severe, severe mental illness,” Alameda County Public Defender Brendon Woods said at the hearing, per East Bay Times.

Cowell is also charged with attempted murder after stabbing Wilson’s sister, Lahtifa Wilson, in the neck. He also received a charge for using a deadly weapon.

It is unclear if the alleged attack was racially motivated, Cowell is White and Wilson was Black, something that Cowell’s lawyer dismissed.

“What we have here is someone who was released by a state hospital just 75 days before this incident,” Woods said. “He suffers from severe mental illness, and that’s why we’re here today.”

Cowell, who is a convicted felon stemming from a 2016 second-degree robbery, will next appear in court on Sept. 14.