Colin Gray, the father of alleged Georgia school shooter Colt Gray, pleaded not guilty Thursday to charges related to the mass shooting in September at Apalachee High School that killed four people.

Attorneys for Colin Gray appeared in court Thursday morning and entered a not guilty plea on his behalf. They also waived a formal arraignment. He was not present for the hearing.

A Barrow County grand jury indicted the older Gray in October on 29 counts, including second-degree murder, second-degree cruelty to children, involuntary manslaughter and reckless conduct, according to online court records.

Barrow County District Attorney Brad Smith said Colin Gray’s charges marked the first time in state history that a parent of a suspect in a school shooting was charged.

His son was indicted separately on 55 counts, including four counts of malice murder and four counts of felony murder, in the Sept. 4 shooting at the Winder high school. The younger Gray, who was charged as an adult, waived his formal arraignment and pleaded not guilty in October, court records show.

Two students and two teachers were killed and nine other people were injured. Those killed were identified as Christian Angulo, 14; Mason Schermerhorn, 14; Richard Aspinwall, 39; and Cristina Irimie, 53.