(FOX 2) - Teenager Tanaya Lewis is accused of fatally stabbing Danyna Gibson - a friend at Warren Fitzgerald High School last September.
In court testimony Friday, Lewis had allegedly threatened, "They have to watch out - they have it coming to them."
That threat was made the night before the stabbing according to Tanaya's ex-boyfriend who said his friend Danyna had told him Tanaya had been cheating on him. That's when Tanaya Lewis made the threat - then this the morning of September 12.
"She texted me and said 'Do you like Danyna?' and I said I don't have to tell you, we're not together," the ex-boyfriend said. "And she goes - 'It's time.'"
But what did that mean? Prosecutors say Tanaya Lewis was about to show everyone.
It was just the seventh day of class, and veteran teacher Sara Sonnenfeld scanned her classroom.
"I heard some kind of a gasp," said teacher Sara Sonnenfeld. "I first see Danyna by the windows - she's running toward me as I'm standing in-between my desks. I see Tanaya continuing to run after her - smiling."
A student testifying about what happened next:
"Tanaya caught onto her and she stabbed her in her upper back," she said.
Attorney: "OK so did you actually see something in Tanaya's hand?"
"Yes," she said. "A knife. I heard her say I'm going to kill you, b----."
The teacher says she grabbed Tanaya and pushed her into the hallway, Tanaya trying to get back in, shouting: "I hope she dies, I hope she dies."
Inside the classroom Danyna was face down in a pool of blood.
"I put my hand on her back and I'm trying to figure out exactly where the blood is coming from," said Sonnenfeld.
The injuries would prove fatal.
In court, defense attorneys suggested defendant Tanaya Lewis is mentally ill. Her ex-boyfriend testified that he thought she needed help.
"I texted why did you do this, there could have been another way," he said. "She never responded."
But the ex-boyfriend says he spoke with Tanaya by phone after the attack.
"I said why did you do it," he said.
"She just kept saying, 'I'm sorry,'" he said.
There has been no decision yet by the judge on this case going to trial. The preliminary exam will continue on March 1.