Gray, 55, was sentenced last week to 15 years behind bars after a jury in March found him criminally culpable for the 2024 school shooting at Apalachee High School in Winder, Georgia. He faced more than 100 years in prison after being found guilty of 27 counts, including second-degree murder.

Gray's defense attorneys filed a motion this week asking for a new trial within 30 days on grounds that the March verdict was "contrary to evidence," "decidedly and strongly against the weight of the evidence" and "contrary to law and the principles of justice and equity."

Colin Gray admitted to gifting the assault rifle used by his then-14-year-old son, Colt Gray, in the September 2024 mass shooting, in which two students and two teachers were killed.

Judge Nicholas Primm told Colin Gray at sentencing that he was convicted because "the warning lights were flashing brighter and brighter," and he didn't get his son help or remove his access to guns.

"No parent thinks that their child is going to be the next school shooter, but it became more and more obvious that something bad was going to happen," Primm said.

The judge said during sentencing that Colin Gray "failed as a parent."

Last month Colt Gray pleaded guilty to all 55 counts against him, including murder and aggravated assault. The teenager was sentenced to life without parole, with the judge calling his actions "deliberate, contemplated evil."

Attorneys for Colin Gray did not immediately respond to a request for comment.