WINDER, Ga. (AP) — A teenager has pleaded guilty to all 55 counts, including murder, in a shooting nearly two years ago at Apalachee High School in Georgia that killed two students and two teachers.

Colt Gray, 16, entered the plea Friday without having reached a deal with prosecutors. The Sept. 4, 2024, shooting also left several others wounded at the school of 1,900 students about 45 miles (73 kilometers) northeast of Atlanta.

Gray, who was 14 at the time of the shooting, was charged as an adult. His trial had been scheduled to start in mid-October.

A jury in March convicted his father, Colin Gray, on charges including second-degree murder and involuntary manslaughter. He is scheduled to be sentenced next week. Prosecutors said he gave his son the assault-style rifle used to open fire at the school.

Teachers Richard “Ricky” Aspinwall, 39, and Cristina Irimie, 53, and students Mason Schermerhorn and Christian Angulo, both 14, died in the shooting. Another teacher and eight more students were wounded, seven of them hit by gunfire.

Teen faces life in prison

Barrow County Superior Court Judge Nicholas Primm questioned Gray to ensure he understood the consequences of his plea and was entering it voluntarily. Gray responded, “Yes, your honor,” each time.

Murder carries a minimum sentence of life in prison. The judge must decide whether Gray should be eligible for parole after hearing victim statements, evidence and each side's summary of the case.

Gray, his legs chained, sat at a table next to his attorney.

Victim: ‘Those decisions were his and his alone’

Family members of those killed and students who were shot gave statements, expressing anger and grief, with most asking the judge to sentence Gray to life without parole.

Breanna Schermerhorn, whose son Mason was killed, said she does not forgive Colt Gray. While adults around him missed warning signs, she said, he decided to bring the gun and to pull the trigger.

“Those decisions were his and his alone,” she said.

Shayna Aspinwall, Richard Aspinwall's wife, lamented that the lives of their daughters, who were 2 and 5 when their father died, will be “forever marked by his absence.”

“It is a life sentence of grief and trauma for those left behind,” she said.

A teenage student who was shot recalled that day, telling the judge she remembered feeling “really scared and confused because I saw Colt standing in the door with a gun.” The Associated Press is not identifying the girl, who is a minor.

She said she realized she had been shot and asked a friend to hold her hand. She asked other friends to call her brother to let him know she'd been shot and didn't know if she'd make it. She had multiple surgeries and wasn't able to walk for about a year.

“After the shooting, I struggled with so much anxiety, and I felt like my life was over,” she said.

Apalachee High School Principal Jessica Rehberg said in court that Colt Gray’s “cruel actions” deserve “the harshest consequences.”

The hearing is expected to extend into next week, and Gray's defense attorney wrote in a court filing that he plans to call a psychologist, a counselor at the juvenile detention center where he has been held and his grandmother to testify.

Investigator says Colt Gray carefully plotted the shooting

Barrow County Sheriff’s Office Investigator Jason Smith testified about the timeline of the shooting based on video footage. Gray told his second period teacher just before 10 a.m. that he needed to see a crisis counselor but instead went to a bathroom to prepare for the shooting, Smith said.

He emerged from the bathroom at 10:21 a.m., and when he was unable to get back into his classroom, he went down the hall to another classroom, where he opened fire and then shot other people in the hallway. He ultimately surrendered to law enforcement officers.

Smith said he interviewed Gray at the school and again at the sheriff’s office.

Prosecutors played an audio recording of Smith interviewing Gray at the school. The teenager is heard sobbing hysterically as he's questioned. He repeatedly apologized, said he wasn't trying to justify his actions and said what he'd done was “horrible" and “the worst nightmare for everyone involved.”

He talked about having uncontrollable urges and hearing people tell him to do things and said he was supposed to see a doctor soon.

“I was so close to getting the help I need and the medication I need,” Gray told Smith.

“Colt indicated that it was spontaneous, that it was a last minute thing,” Smith testified. But the investigation showed that the shooting had been planned in detail for some time, he said.

The investigator described pages of a notebook Gray had that included a detailed step-by-step plan to get himself ready in the bathroom that included notations like, “Don’t shoot anyone in the bathroom. You will alert people.”

On one page he wrote, “I’m not a killer,” and “I’m scared.” On multiple pages, the word “why” was written dozens of times. He also estimated the number of people he would kill and injure. On one page, he wrote, “Surprised if I make it.”

Sheriff’s deputies had previously interviewed Colt and Colin Gray in May 2023 about an online threat linked to the son. Colt Gray denied making the threat.

Investigators also found a shrine in Colt Gray's bedroom to Nikolas Cruz, the shooter in the 2018 massacre at Florida’s Marjory Stoneman Douglas High School, prosecutors have said. Gray told Smith he “became obsessed with him on an emotional level,” referring to Cruz.

An investigator testified during Colin Gray's trial that he had been aware that his son's mental health had deteriorated and sought help from a counseling service weeks before the shooting. But the father never followed through on getting help for his son, the investigator said.

His mother, Marcee Gray, who was separated from Colin Gray, told investigators she had urged him weeks before the shooting to secure his guns and restrict their son’s access to them. Instead, over time, Colin Gray bought the boy ammunition, a gun sight and other shooting accessories, records show.