The 55-year-old gave his teenage son a rifle for Christmas a year before the deadly rampage. He is believed to be the first parent convicted of murder over a shooting carried out by their child.The father of a boy charged with shooting dead four people at a high school in the US state of Georgia was found guilty of murder and manslaughter on Tuesday. Jurors took less than two hours to convict Colin Gray, 55, over the September 2024 shooting at Apalachee High School in Winder, northeast of Atlanta. He was found guilty of second-degree murder in the deaths of two 14-year-old students — Mason Schermerhorn and Christian Angulo — and of involuntary manslaughter in the killings of teachers Richard Aspinwall and Cristina Irimie. What happened during the trial? During the 11-day trial, prosecutors told the court that Colin Gray armed and enabled his son Colt, who was 14 at the time, by giving him a rifle as a Christmas present despite the boy's deteriorating mental health. "This case is about this defendant and his actions, allowing a child that he has custody over access to a firearm and ammunition after being warned that that child was going to harm others," Barrow County district attorney Brad Smith said. According to the FBI, sheriffs interviewed Colt Gray and his father in May 2023 — more than a year before the shooting — after receiving anonymous tips about online threats to commit a school shooting. Prosecutors said Colin Gray ignored warning signs, including that his son maintained a shrine to school shooters and acted violently at home. Defense attorney Brian Hobbs told the jury that Colin Gray, who pleaded not guilty, was unaware of his son's intentions and had sought help for his mental health challenges. He said he was only trying to be a good father and never imagined Colt would carry out the attack. Why is the case significant? It is one of the few cases in the US where a parent has been prosecuted over the actions of their child in a mass shooting. In 2024, the parents of a teenager who shot and killed four people at a Michigan high school three years earlier were convicted of manslaughter charges. In that unprecedented and closely watched case, Jennifer and James Crumbley were sentenced to 10 to 15 years. Colin Gray is believed to be the first parent to be charged with murder over a shooting carried out by their child. What happens next? Colin Gray will be sentenced at a later date. Second-degree murder is punishable by at least 10 but no more than 30 years in prison. He also faces up to 10 years for involuntary manslaughter. Colt Gray, who was 14 at the time of the shooting and is now 16, has been charged as an adult and is yet to stand trial. He has pleaded not guilty to 55 counts. Investigators allege the teen carefully planned the attack on September 4, 2024, when he brought his semiautomatic, assault-style rifle to school in his book bag. Edited by: Dmytro Hubenko