A 16-year old pleaded guilty in a Michigan courtroom on Monday in the shooting to deaths of four classmates last year.

Ethan Crumbley was tried as an adult for the four murders and the injuring of six other students and a teacher during the mass shooting at Oxford High School on November 30, 2021.

The teenager pleaded guilty to 24 charges, including first-degree murder, terrorism causing death, assault with the intent to murder, and possession of a firearm in the commission of a felony.

His legal team withdrew an insanity plea after Crumbley went forward with pleading guilty.

Crumbley testified in court that the gun used in the crime had been purchased for him with his money by his father.

The 16-yer old's parents, James and Jennifer Crumbley will face trial in January on four counts of involuntary manslaughter for allegedly ignoring warning signs in their son that could have stopped the mass shooting.

“We will continue to fight until the truth is revealed about what went wrong leading up to this tragedy, and who, including Crumbley’s parents and multiple Oxford Community Schools employees, could have and should have prevented it,” Ven Johnson, a lawyer representing the victims in a civil lawsuit, told NBC News.