“These charges stem from knowingly allowing his son to possess a weapon,” GBI Director Chris Hosey said in a news conference on Thursday evening.

He said agents would “work tirelessly to complete this investigation as we move forward”, but declined to answer questions about how the child acquired the gun.

The father was arrested by the GBI in co-ordination with Jackson County District Attorney Brad Smith, and is currently being held in custody, officials said.

Authorities are investigating whether the AR-style weapon used in the attack was a gift purchased by Mr Gray in December 2023, law enforcement sources told CBS News, the BBC’s US partner.

CNN reported that the weapon was a holiday present to his son.

In May 2023, the FBI sent local sheriff’s deputies to interview the boy and his father after being alerted to online threats about a school shooting.

The boy, who was 13 at the time, denied posting the comments.

His father told investigators “he had hunting guns in the house, but the subject did not have unsupervised access to them”, the FBI said in a statement on Wednesday.

“At the time, there was no probable cause for an arrest or to take any additional law enforcement action on the local, state or federal levels,” the FBI statement said.

Officials say the threats were made on the Discord social platform, and contained images of guns.