OAKLAND, Calif. (KTVU) - The defense called John Cowell to the stand on Tuesday in his own murder trial stemming from the 2018 stabbing death of Nia Wilson at the MacArthur BART station in Oakland.
As part of his testimony, Cowell admitted to fatally stabbing Wilson, 18, in the neck and trying to kill her sister Letifah. While on the stand he made references to "alien technology” and “fake skin.”
For the first time, Cowell gave his reason for carrying out the attack. He told the jury that Wilson and her sister were aliens and gang members out to kidnap his grandmother.
"I stabbed both of the females in the crew because I believed they would not give my grandmother back," he said.
Cowell told the jury, he's bipolar, schizophrenic and hears voices.
But Wilson's mother Alicia Grayson isn't buying it.
"I believe he's delusional. I think he's delusional now, not then," she said.
On the stand, Cowell gave rambling often incoherent answers at times, talking about miniature radios implanted in his ears. He also mentioned "fake skin," "white skin," and "black skin."
He was often at odds with his own attorney in confirming basic facts and dates.
Many of Nia Wilson's family members believe it's all an act.
"I believe 75% of it is made up, but 25% I think is racially motivated because he keeps talking about black women and gang members," her mother said.
Prosecutor Butch Ford vigorously cross-examined Cowell and asked if it was true he was a drug and alcohol abuser. Ford also brought up other damaging aspects of the defendant's past, and each time, Cowell replied, "I don't remember."
He repeatedly snapped during questioning from Ford and accused the prosecutor of being rude and disrespectful.
Grayson believes the attack on her daughter was based on the girl's skin color, even though the district attorney hasn't charged a hate crime.
"Then he also said 'light skin,' 'dark skin,' and 'fake skin' and that's what made me think you know racially motivated," Grayson said.
Cowell's testimony followed an emotional day in court during which Wilson's sisters, Tashiya and Letifah, tearfully described her final moments as they watched her holding her neck where she was stabbed.
They both broke down while on the stand Monday, prompting Judge Allan Hymer of Alameda County Superior Court to call for recesses to give them a chance to compose themselves.
"For them to have to witness something like that, you know, I couldn't even imagine it, that's my baby girl," Grayson said outside of court Monday.
Cowell is accused of killing Wilson and trying to kill her sister Letifah by stabbing them both in the neck at the MacArthur BART Station in Oakland.
Letifah watched BART surveillance video in court Monday showing her and her two sisters riding in the same BART car as Cowell from the Concord station. But she began crying and told prosecutor Butch Ford, "I can't go on," as he asked her questions about the moments before the attack. Letifah then became sick in court.
Both Letifah and her sister Tashiya told the jury they saw Wilson falling or tripping into the BART train and then realizing that she had been stabbed from behind on the station platform. Wilson then called out Letifah's name. Surveillance video shows the 18-year-old holding her neck in shock.
Tashiya testified, "I was in shock. I was trying to figure out what happened."
She said Wilson was holding ner neck and that blood was coming out of her mouth. Tashiya said she called her father and starting yelling into the phone to come to the station.
Grayson said it was gut-wrenching for Wilson's sisters to relive her last moments.
"She got like physically sick on the stand," said Grayson referring to Letifah. "The other one, I could just see it in her face, like disgust."
Wilson's mother has been in court every day, unlike Cowell, who has repeatedly refused to come to his own trial. He's pleaded not guilty by reason of insanity.
"Maybe that's part of his strategy because any sane person would be in court," Grayson said.