Oxford High School shooting suspect Ethan Crumbley will pursue a legal defense of insanity, according to a legal notice filed Thursday in a Michigan district court.

Crumbley, 15, is accused of fatally shooting four students and injuring seven others at Oxford High School on Nov. 30. The four deceased victims are 16-year-old Tate Myre, 14-year-old Hana St. Juliana, 17-year-old Madisyn Baldwin and17-year-old Justin Shilling. 

His defense attorneys Paulette Loftin and Amy Hopp said in a court filing that their client "intends to assert the defense of insanity at the time of the alleged offense" in the filing, according to the Detroit Free Press.

Loftin did not immediately respond to an inquiry from Fox News Digital.

Ethan Crumbley, 15, allegedly shot and killed four students and injured seven others at Oxford High School. His mother allegedly texted him,

Ethan Crumbley, 15, allegedly shot and killed four students and injured seven others at Oxford High School. (Oakland County Sheriff's Office)

Crumbley pleaded not guilty earlier this month to 24 charges, including first-degree murder and terrorism, in connection with the mass shooting. His parents, James and Jennifer Crumbley, also face four counts of involuntary manslaughter each.

Oakland County prosecutor Karen McDonald revealed in December that school officials met with Crumbley and his parents to discuss violent drawings he created just hours before the deadly rampage. 

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The 15-year-old suspect was able to convince them during the meeting that the concerning drawings were for a "video game." His parents "flatly refused" to take their son home. 

Oxford Community Schools Superintendent Tim Thorne said in a December letter to the school community that a teacher had observed "concerning drawings and written statements" from Crumbley and reported it to the dean of students and school counselors on the morning of the Nov. 30 shooting.

"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 said at the time.

James and Jennifer Crumbley appear before an Oakland County court in Michigan on Dec. 14, 2021. (Fox News' Audrey Conklin)

James and Jennifer Crumbley appear before an Oakland County court in Michigan on Dec. 14, 2021. (Fox News' Audrey Conklin)

Forensic psychiatrist Dr. Ziv Ezra Cohen says that because this is a high-profile case with evidence that may Crumbley was mentally unstable at the time of the shooting, such as drawings and social media posts, the prosecution is "playing with a double-edged sword."

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"They made public information [that] portrayed the defendant as a very troubled individual, but of course, that cuts both ways. If the individual is very troubled, that does potentially open up the possibility of a mental health defense," Cohen, a clinical assistant professor of psychiatry at Weill Cornell Medical College of Cornell University and staff member of New York-Presbyterian Hospital, told Fox News.

The shooting has also resulted in several lawsuits, including one filed Thursday on behalf of the parents of four Oxford High School students, including deceased Tate Myre, as well as minors Keegan Gregory, Sophia Kempen and Grace Kempen. The suit accuses James and Jennifer Crumbley and school staff of negligence.

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"What our lawsuit lays out … is the overwhelmingly substantial evidence that, clearly, Ethan Crumbley was a mentally ill child that needed significant intervention," attorney Ven Johnson, president of Ven Johnson Law, said during a Thursday press conference. "And we've heard the term ‘therapy’ in this case. He didn't need therapy on Nov. 30. What he needed was … to be hospitalized and evaluated."

Tate Myre (Credit: Johnson Law, PLC)

Van Johnson continued: "That day, he needed to be taken to an emergency room and seen."

Another lawsuit – seeking $100 million in damages each against the school district and school employees on behalf of Jeffrey Franz and Brandi Franz, the parents of two sisters who attend the school – alleges Crumbley posted direct threats to social media before he allegedly shot numerous people inside Oxford High School.

"Previous to the Nov. 30, 2021, incident, Ethan Crumbley posted countdowns and threats of bodily harm, including death, on his social media accounts, warning of violent tendencies and murderous ideology prior to actually coming to school with the handgun and ammunition to perpetuate the slaughter," the lawsuit states.

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Crumbley allegedly posted this statement to his Twitter account on the night before the shooting, according to the lawsuit: "Now I am become Death, the destroyer of worlds. See you tomorrow Oxford."

Cohen noted that "less than 1%" of defendants who claim insanity succeed, "so it's unlikely that he's going to succeed with the insanity defense," but his age "could play into his favor even though he's being tried as an adult.

Cohen says experts are often brought into criminal cases to offer psychiatric evaluations of a defense arguing insanity, though a defense "could present an insanity case purely using lay testimony" if thought it could help their case to do so.