Oxford Community Schools superintendent Tim Thorne has explained the events leading up to the fatal shooting last Tuesday.
Chief suspect Ethan Crumbley was sent back to class despite multiple warning signs, including concerning drawings found on his desk. After being dismissed from the counselor's office, the 15-year-old open-fired, killing four students and injuring seven other people.
In a letter addressed to the community on Saturday, later obtained by CNN, Thorne expressed his gratitude to the teachers, students, and first responders for their actions.
He then disclosed that the school has requested a third-party investigation into Crumbley's actions, before going on to give more details about the events.
Thorne described how on November 29, a teacher observed Crumbley looking up pictures of ammunition on his phone during class. He then met with a counselor and other staff members but convinced them that he was only interested in bullets as shooting was a family hobby.
The school attempted to speak with Crumbley's parents, but could not make contact until the following day when they confirmed their son's account.
On the day of the shooting - November 30 - Thorne recounts how a teacher "observed concerning drawings and written statements" on Crumbley's desk. Prosecutors revealed this week that these doodlings depicted a gun, a bullet, a shooting victim, and a laughing emoji.
The words "thoughts won't stop, help me," "the world is dead," and "my life is useless," were also written on the note.
"The student was immediately removed from the classroom and brought to the guidance counselor's office, where he claimed the drawing was part of a video game he was designing and informed counselors that he planned to pursue video game design as a career," Thorne wrote in the letter.
He then describes how Crumbley was kept in the guidance counselors office while waiting for his parents to arrive. During this time, the 15-year-old expressed concern over missing class and requested he be allowed to finish his science homework.
"At no time did counselors believe the student might harm others based on his behavior, responses, and demeanor, which appeared calm," Thorne wrote. He added that despite media reports, it has not been confirmed whether a gun was in Crumbley's backpack during this time.
When Crumbley's parents arrived he was further questioned, but again Thorne relays that his responses gave the school authorities no cause for concern.
Thorne also claims that Crumbley's parents did not disclose that they had given their son a firearm and that when asked if they could take him home they "flatly refused."
"Given the fact that the child had no prior disciplinary infractions, the decision was made he would be returned to the classroom rather than sent home to an empty house," wrote Thorne.
"While we understand this decision has caused anger, confusion and prompted understandable questioning, the counselors made a judgment based on their professional training and clinical experience and did not have all the facts we now know," he continued.
After briefly appearing to go on the run, Crumbley's parents were arrested in Detroit on Saturday morning, Independent reports.
Ethan Crumbley has been charged with four counts of first-degree murder, one count of terrorism causing death and other crimes. Both of his parents have been charged with four counts of involuntary manslaughter.
All three members of the Crumbley family have pleaded not guilty to all charges.