A Georgia jury has found a father guilty of murder and other charges, holding him criminally responsible for giving his son a rifle that prosecutors say was used in a deadly 2024 school shooting.

On March 3, the jury convicted 55-year-old Colin Gray on 27 counts, including two counts of second-degree murder, two counts of involuntary manslaughter, 18 counts of cruelty to children, and five counts of reckless conduct, in connection with the mass shooting allegedly carried out by his son, Colt Gray.

Prosecutors said Gray bought his then-14-year-old son an AR-15-style rifle as a Christmas present and allowed him access to the weapon and ammunition despite repeated warnings that the boy posed a danger to others.

They say the younger Gray took that rifle onto a school bus, then left his second-period class at Apalachee High School in Winder, Georgia, on Sept. 4, 2024. According to prosecutors, he emerged from a bathroom with the rifle and opened fire in a classroom and nearby hallways, killing two teachers and two students and wounding nine others.

The indictment against Colin Gray alleged his actions amounted to “criminal negligence” and that he “consciously disregarded a substantial and unjustifiable risk.”

“That man and his son are both responsible for the immense suffering that occurred on September 4,” prosecutor Patricia Brooks told jurors in her closing argument. “The blood is on their hands.”

The defense argued that while Gray may have been a permissive parent, he had no knowledge of any plan by his son to carry out a shooting.

“What never enters your mind, as a parent who loves their child, is that they could plan to carry out a horrific shooting,” defense attorney Jimmy Berry told the jury. “We always want to see the best in our children.”

Berry also stressed that Georgia law does not require gun owners to lock up firearms or keep them in a gun safe away from children. He also described the teenager as “secretive” and “very manipulative,” arguing that Colt could have found a way to carry out the attack even if his father hadn’t bought him the rifle.

Testifying in his own defense, Colin Gray recounted incidents in which his son said he felt bullied at school and sometimes displayed intense anger. Still, he said he never saw his son as a violent threat.

“I never thought that he would even have a thought process of bringing a gun to school or doing any kind of harm to anybody else—well, on anybody at school,” Gray told jurors.

It took less than two hours of deliberation for jurors to reach a guilty verdict. Prior to that, they heard two weeks of testimony, including body-camera footage from May 21, 2023, when county police deputies visited the Gray home after the FBI received an online tip about a threat to shoot up a school. Colt denied making the threat, and investigators were unable to substantiate it. Later that year, Colin Gray bought the rifle for his son.

The teenager’s mother, Marcee Gray, wasn’t charged. She and Colin Gray were separated in the months leading up to the shooting, and Colt Gray lived mostly with his father during that time.

She testified during the trial that she had urged her estranged husband to take any guns and lock them inside his truck so they would not be accessible to their son.

Colin Gray’s sentencing has not yet been scheduled. He faces 10 to 30 years in prison on each second-degree murder count and 1 to 10 years on each involuntary manslaughter count, in addition to potential penalties on the remaining charges.

Colt Gray, now 16, remains in custody. He has been charged as an adult with 55 counts, including four counts of murder in the deaths of 14-year-olds Mason Schermerhorn and Christian Angulo, and teachers Richard Aspinwall, 39, and Cristina Irimie, 53, as well as 25 counts of aggravated assault. He pleaded not guilty.

A trial date for him has not yet been set.

The Associated Press contributed to this report.