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, but a news conference was planned for later in the day.

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 AP 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 Associated Press 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 interview transcript quotes the teen as saying: "I promise I would never say something where ..." with the rest of that denial listed as inaudible.

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.

The attack was the latest among dozens of school shootings across the U.S. in recent years, including especially deadly ones in Newtown, Connecticut; Parkland, Florida; and Uvalde, Texas. The classroom killings have set off fervent debates about gun control and frayed the nerves of parents whose children are growing up accustomed to active-shooter drills. But there has been little change to national gun laws.

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.

When the suspect slipped out of math class Wednesday, Lyela Sayarath figured her quiet classmate who recently transferred was skipping school again. But he returned later and wanted back into the room. Some students went to open the locked door but instead backed away.

"I'm guessing they saw something, but for some reason, they didn't open the door," Sayarath said.

The teen then opened fire in the hallway, authorities said.

Sayarath said she heard a barrage of 10 to 15 gunshots. The students fell to the floor and crawled in search of a safe corner to hide.

Two school resource officers confronted the shooter within minutes after the gunshots were reported, Hosey said. The teen immediately surrendered.

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.

Prior cases have emerged in which someone who was once on the FBI's radar but was not arrested went on to commit violence.

A month before Nikolas Cruz killed 17 people at the Parkland, Florida, high school in 2018, the bureau received a warning that he had been talking about committing a mass shooting. The FBI also investigated a tip about the person later convicted in a deadly 2022 shooting at a gay nightclub in Colorado.

The pattern underscores the challenges law enforcement faces in trying to determine when concerning behavior crosses into a crime. Investigators sift through tens of thousands of tips every year to try to determine which could yield a viable threat. Cases such as the Georgia school shooting prompt fresh questions about whether more intensive investigative work might have averted the violence.

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.

He described a photo on his cellphone from a recent hunting trip with his son: "You see him with blood on his cheeks from shooting his first deer." Gray's father called it "the greatest day ever."

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

"I gotta take you at your word and I hope you're being honest with me," Miller replied.

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."

Tags: Georgia  Atlanta  Barrow County  school shooting  North Georgia