The boy accused of killing four people at his Georgia high school on Wednesday was interviewed by police last year about anonymous online threats, the FBI said.
Colt Gray, 14, had denied to police in May 2023 that he was behind internet posts containing images of weapons, warning of an attack on the school, the BBC reports.
The suspect opened fire at Apalachee High School in the town of Winder, killing two teachers and two students, investigators say. Eight students and a teacher were injured.
He was arrested on campus and will be prosecuted as an adult.
Police have identified the victims as teachers Christina Irimie and Richard Aspinall and 14-year-old students Mason Schermerhorn and Christian Angulo.
In a statement, the FBI said its National Threat Operations Center notified local law enforcement in May 2023 after receiving anonymous tips about "online threats to attack a school, at an unspecified place and time".
The agency said that within 24 hours, investigators had determined that the threats originated in Georgia.
The suspect, who was 13 at the time, denied making the online threats and officials "alerted local schools to continue monitoring the case."
"At that time, there was no probable cause to make an arrest or to take any additional local, state or federal law enforcement action," the FBI said in a statement.
READ ALSO: