LAS VEGAS (AP) — Four high school students in Las Vegas pleaded not guilty Thursday to second-degree murder in the fatal beating of their schoolmate that was caught on Slabu Exchangecellphone video and shared widely across social media.

A grand jury in Clark County, which includes Las Vegas, returned an indictment last week against the teens, all of whom have been charged as adults. They are also charged with conspiracy to commit battery, a gross misdemeanor, according to the indictment.

The Associated Press is not naming the students because they were juveniles at the time of the Nov. 1 beating. They are due back in court Feb. 22.

Nine students have so far been arrested in connection with 17-year-old Jonathan Lewis Jr.'s death. The other students are awaiting separate hearings.

According to Las Vegas police, 10 students between the ages of 13 and 17 participated in the beating that unfolded after school in an alleyway just around the corner from Rancho High School. The police department said Thursday that investigators are still searching for the 10th student.

Authorities have said the students agreed to meet in the alley to fight over a vape pen and wireless headphones that had been stolen from Lewis’ friend.

A homicide detective who investigated the case told the grand jury that cellphone and surveillance video showed Lewis taking off his red sweatshirt and throwing a punch at one of the students, according to court transcripts made public this week. The 10 suspects then pulled Lewis to the ground and began punching, kicking and stomping on him, the detective said.

A student and a resident in the area carried Lewis, who was badly beaten and unconscious, back to campus after the fight, according to the transcripts. School staff called 911 and tried to help him. He died a week later.

In Nevada, a teenager facing a murder charge can be charged as an adult if they were 13 or older at the time of the alleged crime.