The man who fatally stabbed 18-year-old Nia Wilson was sentenced on Friday (July 17) to life in prison without the possibility of parole. John Lee Cowell was found guilty of murdering Wilson and attempting to murder her sister, Letifah Wilson. He originally pleaded not guilty by reason of insanity, but an Alameda County judge ruled that he was sane at the time of the attack.

Cowell was diagnosed with schizophrenia and his defense team claimed that his mental illness caused him to have a “psychotic break” from reality. During his testimony, he claimed that he believed Wilson and her sisters were “gang members” and “aliens” and said they kidnapped his grandmother.

“There were three black females working together. They were staring me down. It’s not illegal to said, save, or rescue a family member. I stabbed the females because they would not give my grandmother back,” Cowell told the jury.

The lead prosecutor told the jury that Cowell was pretending to be “crazy.” Video surveillance proved that the homicide was premeditated. He rode on the same train as the sisters for almost 30 minutes, followed them and then stabbed them as they were getting on another train. He then left the BART station, changed his clothes, hid the knife and got on a bus.

“The horrific killing of Nia Wilson and the assault on her sister will haunt her family, loved ones and our community forever. Mr. Cowell will now serve the remainder of his life in prison. It is my hope that Nia’s family feels that justice was served and can continue on the path of healing,” District Attorney Nancy O’Malley said.

Wilson’s family believes that the 2018 attack was racially motivated. Some of her family members spoke at the hearing Friday. “You stole my baby sister from her loving family because of your hatred toward Black African-American women,” Wilson’s sister Letifah said to Cowell.

“I just want to say, thank God justice was served,” said Alicia Grayson, Nia Wilson’s mother. “And he just better pray to God that he can sleep every night and continue on living.”