WINDER, Ga. — The father of the teenager accused of opening fire at a Georgia high school, killing four people and wounding nine, has been arrested on various charges including second-degree murder, authorities said Thursday.

Colin Gray, 54, the father of Colt Gray, was charged with four counts of involuntary manslaughter, two counts of second-degree murder and eight counts of cruelty to children, the Georgia Bureau of Investigation said in a social media post. No other details were immediately provided.

In Georgia, second- degree murder means that a person has caused the death of another person while committing second-degree cruelty to children, regardless of intent. It is punishable by 10 to 30 years in prison, while malice murder and felony murder carry a minimum sentence of life.

Authorities have charged 14-year-old Colt Gray as an adult with murder in the shootings Wednesday at Apalachee High School outside Atlanta. Arrest warrants obtained by The Associated Press accuse him of using a semiautomatic assault-style rifle in the attack, which killed two students and two teachers and wounded nine other people.

The teen denied threatening to carry out a school shooting when authorities interviewed him last year about a menacing post on social media, according to a sheriff’s report obtained Thursday.

Conflicting evidence on the post’s origin left investigators unable to arrest anyone, the report said. Jackson County Sheriff Janis Mangum said she reviewed the report from May 2023 and found nothing that would have justified bringing charges at the time.

“We did not drop the ball at all on this,” Mangum told the AP in an interview. “We did all we could do with what we had at the time.”

When a sheriff’s investigator from neighboring Jackson County interviewed Gray last year, his father said the boy had struggled with his parents’ separation and often got picked on at school. The teen frequently fired guns and hunted with his father, who photographed him with a deer’s blood on his cheeks.

“He knows the seriousness of weapons and what they can do, and how to use them and not use them,” Colin Gray said according to a transcript obtained from the sheriff’s office.

The teen was interviewed after the sheriff received a tip from the FBI that Colt Gray, then 13, “had possibly threatened to shoot up a middle school tomorrow.” The threat was made on Discord, a social media platform popular with video gamers, according to the sheriff’s office incident report.

The FBI’s tip pointed to a Discord account associated with an email address linked to Colt Gray, the report said. But the boy said “he would never say such a thing, even in a joking manner,” according to the investigator’s report.

The investigator wrote that no arrests were made because of “inconsistent information” on the Discord account, which had profile information in Russian and a digital evidence trail indicating it had been accessed in different Georgia cities as well as Buffalo, New York.

Classes were canceled Thursday at the Georgia high school, though some people came to leave flowers around the flagpole and kneel in the grass with heads bowed.

Gray was being held Thursday at a regional youth detention facility. His first court appearance was scheduled for Friday morning.

He has been charged in the deaths of students Mason Schermerhorn and Christian Angulo, both 14, and teachers Richard Aspinwall, 39, and Christina Irimie, 53, according to Georgia Bureau of Investigation Director Chris Hosey.

At least nine other people — eight students and one teacher at the school in Winder — were wounded and taken to hospitals. All were expected to survive, Barrow County Sheriff Jud Smith said.

Authorities have not offered any motive or explained how the suspect obtained the gun and got it into the school of roughly 1,900 students in a rapidly developing area on the edge of metro Atlanta’s ever-expanding sprawl.

It was the 30th mass killing in the U.S. so far this year, according to a database maintained by The Associated Press and USA Today in partnership with Northeastern University. At least 127 people have died in those killings, which are defined as events in which four or more people die within a 24-hour period, not including the killer — the same definition used by the FBI.

The sheriff’s report says investigator Daniel Miller spoke to the boy and his father May 21, 2023. The father said his son had access to guns in the house.

“I mean they aren’t loaded, but they are down,” Gray’s father said, according to the interview transcript.

The teen told Miller he stopped using Discord a few months earlier after his account got hacked.

A phone number associated with the account was linked to a different person in another Georgia city, the report said. The account’s profile name, written in Russian, translated to Lanza. The investigator noted that Adam Lanza was the perpetrator of the 2012 mass shooting that killed 26 people at Sandy Hook Elementary School in Newtown, Connecticut.

The sheriff’s office alerted local schools for continued monitoring of the teen. But the investigator concluded that he “could not substantiate the tip I received from the FBI to take further action.”