, who was sporting a white face mask and glasses, was seated with his hands handcuffed in front of him and wearing what appeared to be an anti-suicide vest.
His parents Jennifer and James also attended the arraignment via video.
The alleged gunman only spoke when asked by the judge to state his name and whether he understood the charges against him.
During the court hearing, prosecutors revealed that investigators recovered a video of Crumbley recorded the night before where he discussed killing students.
Crumbley was denied bail and will remain behind bars, isolated from other adult inmates.
The 15-year-old faces life in prison if found guilty.
PREVIOUS THREATS Crumbley is currently being held at a juvenile detention facility, where he has been placed on suicide watch - with someone checking on him every 15 minutes. He is set to be arraigned on Wednesday afternoon.
MacDonald called for better gun laws, saying: "If the incident yesterday with four children being murdered and multiple kids being injured is not enough to revisit our gun laws, I don't know what is."
Eight others, including a teacher, were injured in the shooting on Tuesday afternoon at the high school in Oxford, .
It emerged on Wednesday that had a deer's head dumped on its grounds and was covered in red paint just days before the shooting.
School administrators had posted two letters to parents on the school’s website in November, saying they were responding to rumors of a threat against the school following a bizarre vandalism incident.
Both the sheriff and undersheriff emphasized that Tuesday’s shooting was unrelated to the deer head or any earlier investigation by their office.
“That was a different incident, different student,” Undersheriff Mike McCabe said.
But according to a November 4 letter written by Principal Steve Wolf, someone threw a deer head into a courtyard from the school’s roof.
They also painted several windows on the roof with red acrylic paint and used the same paint on the concrete near the school building during the early morning hours.
Without specifically referencing that incident, a second post on November 12 assured: “there has been no threat to our building nor our students.”
But one concerned parent, Robin Redding, said her son, Treshan Bryant, is a 12th grader at the school but stayed home Tuesday.
Redding said her son had heard threats that there could be a shooting.
“This couldn’t be just random,” she said.
On Wednesday, Sheriff Bouchard said Crumbley and his parents met with school administrators the morning of the shooting due to concerns about the 15-year-old’s behavior the day before.
However, the sheriff said the school never contacted law enforcement about their concerns.
THREATS 'FOR A LONG TIME' Bryant said he texted several younger cousins in the morning and they said they didn’t want to go to school, and he got a bad feeling.
He asked his mom if he could do his assignments online.
Bryant said he had heard vague threats “for a long time now” about plans for a shooting.
Tate Myre, 16, Hana St. Juliana , 14, and 17-year-old Madisyn Baldwin were on Tuesday named as the three victims of the shooting .
Tate was a "standout" football player and died from his injuries on the way to the hospital in the back of a patrol car.
Classmates said that he tried to disarm the shooter.
Crumbley had previously posted about a gun Credit: Instagram James and Jennifer Crumbley are both facing charges of involuntary manslaughter Credit: Facebook/jcrumbley
Ethan Crumbley's mom Jennifer text him 'don't do it' after telling 'school shooter' son to 'learn not to get caught'
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