The teenager who killed two students and two teachers in a 2024 shooting at Georgia’s Apalachee High School had a chaotic, lonely upbringing and immersed himself in an online community of people interested in mass shootings, a psychologist testified Monday.

Colt Gray, 16, pleaded guilty Friday to 55 charges, including murder, in the Sept. 4, 2024, shooting that also left several people injured at the school about 45 miles (73 kilometers) northeast of Atlanta.

He pleaded guilty without reaching an agreement with prosecutors. The murder carries a minimum sentence of life in prison, and it is up to Barrow County Superior Court Judge Nicholas Primm to decide whether he will be eligible for parole after hearing testimony and considering the evidence.

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

A forensic psychologist who evaluated Gray after the shooting at the request of the teen’s attorney testified that during their first meeting in May 2025, Gray asked him if he could put his arms inside the sweatshirt to wrap them around himself.

“I thought he was a little strange kid,” Kevin Richards said. The psychologist said he did four interviews with Gray for a total of about 15 hours and also spoke with Gray’s mother twice for a total of about three hours.

“It was pretty chaotic,” the psychologist said of Gray’s upbringing, noting that the family had financial problems and moved a lot, so he was not enrolled in school for long periods. His parents used drugs and fought a lot, and Gray had a lonely and abandoned childhood, Richards testified.

Gray was paranoid, Richards said. He spoke of his fear that teachers were plotting against him and that people in public were gossiping about him. The teen also believed his home computer had been hacked, prompting him to continue changing usernames and destroying external storage devices, the psychologist said.

Richards said that while he believes Gray experienced paranoia, he doubts that motivated the attack.

“I don’t think he was driven by hallucinations or delusions to do what he did. I think he planned it,” Richards said.

Most of the teen’s social life took place online, Richards said. He was a gamer, but he also found himself immersed in a community of young true crime enthusiasts who were particularly fascinated by mass shootings. Initially, Gray focused on Adam Lanza, who killed 26 people at Sandy Hook Elementary School in Connecticut, as well as James Holmes, who killed 12 people at a Colorado movie theater. Richards said Gray was particularly interested in Nikolas Cruz, the shooter in the 2018 massacre at Florida’s Marjory Stoneman Douglas High School.

“He had just disappeared on Discord and disappeared into the real criminal community,” Richards said.

District Attorney Brad Smith showed Richards some of Gray’s online conversations on Discord, an online communication platform. They established that Gray sometimes lied about his own mental health symptoms and his drugs when speaking to people online to establish common ground with them and gain attention.

When Smith asked if Gray studied and emulated school shooters, Richards responded that Gray was “a little obsessed” with them.

After Gray pleaded guilty Friday, the judge heard impact statements from family members of those killed and shooting victims. The majority asked the judge to sentence him to life in prison without the possibility of parole.

Prosecutors also played recordings of two interviews the lead investigator did with Gray, one that took place less than an hour after the school shooting and another that took place several hours later at the sheriff’s office. During those interviews, the teen mentioned uncontrollable impulses and hearing people tell him to do things.

In March, a jury convicted his father, Colin Gray, of charges including second-degree murder and involuntary manslaughter. He is scheduled to be sentenced later this week. Prosecutors said he gave his son the assault rifle used to open fire at the school.