Opening statements and witness testimony launched Monday in the murder trial for a former Texas high school student accused of fatally stabbing a classmate in 2022.

Prosecutors said Caysen Allison, then 18, stabbed Jose Luis “Joe” Ramirez Jr., 18, multiple times during a fight involving several students on May 18, 2022, at Belton High School in Belton.

Police arrested Allison shortly after the incident and found a folding knife at his home, covered in what appeared to be blood.

A judge reduced his Allison’s from $1 million to $175,000 in July 2022, allowing his release. He has remained on house arrest since.

According to an arrest affidavit, Allison, now 21, waived his right against self-incrimination and told detectives he fatally stabbed Ramirez during a fight in a school restroom.

Prosecutor John Erskin told jurors in opening statements that Ramirez swung first during a fight tied to a post-prom altercation. He cited witness accounts from teachers, school staff, and a student’s recording of the incident.

Defense attorney Zachary Boyd said Allison acted in self-defense after five people attacked him in a restroom with a four-person occupancy limit.

“Caysen survived what could have very well been death or bodily injury by a group beat down,” Boyd said, according to KWTX, adding that the defendant was “in the fight for his life when he was jumped by five friends.”

Jurors watched security footage showing Ramirez and three others walking into a school restroom, followed shortly by Allison and another boy. Five boys, including Ramirez, then ran out of the restroom.

Moments later, Allison ran out as well.

Additional footage showed Ramirez bleeding as he ran down the main hallway before collapsing. School staff reportedly cut Ramirez’s shirt open to find a “gaping wound across his left chest.”

One of the first witnesses to render aid to Ramirez testified that his “breathing was rapid, shallow and appeared as if he had a punctured lung.”

Regina Cox, Belton High’s nurse, testified to finding a “gaping, laceration” on Ramirez after helping staff members stop the bleeding.

Belton High School teacher Willie Ward was one of the staff members who helped, and testified that he called for that Ramirez collapsed near him in the school hallway.

Ward said he had gone to the main hall to check the state testing schedule when Ramirez ran past him, bleeding heavily, before collapsing. Ward knelt beside him and applied pressure to a chest wound. When staff tore open Ramirez’s shirt, Ward said he could see exposed heart muscle.

Defense attorneys focused their questions on Ward’s knowledge of the students involved, details of the incident, and the school’s lack of metal detectors.

Allison told detectives he stabbed Ramirez only once, but a hospital examination indicated that the had been stabbed in the legs, arm, back and chest.

Ramirez’s mother previously told KWTX that her son and the defendant had planned to have a weapons-free fight after school and off-campus, which sparked over a girl and an issue at prom.

“With my boys, I always feared that they’d get in a fight. The world is just getting uglier. People don’t just solve things and move on, they go to this extent for just the stupidest reasons, over a girl,” the mother said, adding that she had never heard of the defendant prior to the fight.

“We never even knew this was a problem. Nobody talked to us. My boys didn’t tell me anything about what happened at prom.”

If convicted, Allison could face life behind bars.

The trial continues. Check back for updates.

[Feature Photos: Joe Ramirez/Handout; Caysen Allison/Benton County PD]