The suspect of a Michigan school shooting recorded videos in which he talks about killing students the night before the incident, NBC News reports.
Authorities investigating the tragic event found the recordings on suspect Ethan Crumbley's phone. The shooting at a high school in Oxford, Michigan, occurred on Tuesday, November 30, and left four students dead.
Oakland County Sheriff's Lt. Tim Willis revealed that the videos had been discovered on Wednesday, just before 15-year-old Crumbley's arraignment.
The disclosure came as news that the fourth victim had passed away in hospital after sustaining fatal injuries in the shooting.
Crumbley was charged in Oakland County district court with four counts of first-degree murder, one count of terrorism causing death, and other crimes. He is being tried as an adult.
Alongside the videos, authorities also found a journal with entries that mentioned shooting and killing students. Further details about the videos and journals are still yet to be disclosed.
Crumbley's lawyer Scott Kozak declined to comment on the findings. The 15-year-old suspect has pleaded not guilty to his charges.
A probable causing hearing is scheduled for December 13. In the meantime, Crumbley will be kept isolated from other inmates at Oakland County Jail, where he is due to be transferred from the juvenile detention facility where he is currently being held.
The first three victims died on Tuesday, and have been confirmed as 14-year-old Hana St. Juliana, 16-year-old Tate Myre, and 17-year-old Madisyn Baldwin.
The fourth victim, 14-year-old Justin Shilling, died on Wednesday after sustaining critical gunshot wounds to the jaw and head.
Alongside the four students who were killed, eight other people - including a teacher - were seriously wounded. Three of these injured victims remain in critical condition.
Police took Crumbley into custody just minutes after they arrived at the scene of the attack. It is believed that he opened fire with a 9mm Sig Sauer handgun that his father had recently bought.
According to Oakland County Prosecutor Karen McDonald, investigators have already uncovered a "mountain" of evidence against Crumbley proving the shooting was a premeditated attack.
"This was not an impulsive act," she said.