OAKLAND, Calif. - The man accused of stabbing to death a woman and injuring her sister on a train platform in the San Francisco Bay Area testified in his trial Tuesday, saying he believed the women were aliens and part of a gang that had kidnapped his grandmother.

“I stabbed both of the females in the crew, because I believed they would not give my grandmother back,” John Lee Cowell, 29, said from the witness stand in Alameda County court, the San Francisco Chronicle reported.

Cowell has pleaded not guilty by reason of insanity in the 2018 killing of 18-year-old Nia Wilson and the stabbing of her sister, Letifah Wilson, who was seriously injured.

During his testimony Tuesday, he said he has a history of mental illness and heard voices in his head. But he could not remember what those voices told him.

Just before the fatal stabbing on July 22, 2018, Cowell rode the train from Concord to the MacArthur station in Oakland along with Nia Wilson and two of her sisters.

During direct examination, Cowell spoke about a radio in his head and said the three women were “pointing to other passengers while staring at me.”

He added that he felt “threatened by three black females. They were together ... threatening to assault my grandmother.”

Surveillance footage of the entire 25-minute ride shows no interaction between Cowell or any of the sisters.

Cowell is charged with one count of murder and one count of attempted murder for the double stabbing.

Police and prosecutors said the knife attack was unprovoked, while friends and family members of Nia Wilson have said they believe the attack was motivated by the women’s race. The Wilson sisters are black, and Cowell is white.

Cowell testified that about a week before the train ride with the Wilson sisters, he had been punched in the face by a black female.

Prosecutor Butch Ford pounced on Cowell’s mention of the sisters’ race, specifically asking the defendant if he stabbed the women because they were black females.

Ford asked if it was true that Cowell attempted to pick a fight with another black female on a bus just after the stabbing.

Reading from what he said was a transcript of footage from the bus ride, Ford asked Cowell if he told he woman, “You’re trying to throw something on me, you little n—?”

Several people in the spectator gallery gasped at the racial slur. Cowell's attorney, Christina Moore, objected, saying the statement was never introduced into evidence and was inaccurate.

“That’s being fabricated by Mr. Ford,” Moore said, before calling for a sidebar with Ford and Judge Allan Hymer.

On Monday, Nia Wilson’s sisters, Tashiya and Letifah, recalled the horrific moments after the stabbing as their little sister bled out on the train platform.

“I looked at her like, ‘What’s going on?’ ” Tashiya Wilson, 22, told the courtroom through tears, adding that Nia was clutching her neck. “I just see blood on her hands.”

Police said Cowell pulled a hood over his head and put on sunglasses just before the attack. He also allegedly discarded his backpack and clothing in the station’s parking lot to avoid arrest. He was taken into custody a day later at BART’s Pleasant Hill Station.

News from © The Associated Press, 2020