211202 shooting
Mourners react as they visit a makeshift memorial outside of Oxford High School on December 01, 2021 in Oxford, Michigan. Image Credit: AFP

The teenage student accused of killing four classmates in a shooting rampage at a Michigan high school last year is expected to plead guilty to two dozen charges, authorities said Friday, including terrorism — an extraordinarily unusual if not unprecedented charge in a school shooting.

Oakland County Chief Assistant Prosecutor David Williams said in a statement that Ethan Crumbley, who was 15 when he allegedly opened fire at an Oxford, Michigan, school and is being charged as an adult, is expected to plead guilty Monday to four counts of first-degree murder, seven counts of assault with intent to murder, 12 counts of possession of a firearm and one count of terrorism causing death.

"There have been no plea deals, no reductions and no sentencing agreements," Williams said. In addition to the four killed, seven were wounded in the shooting.

The terrorism charge was designed to address the harm caused to those who suffered from the violent rampage but who were not killed or injured, Oakland County Prosecutor Karen McDonald told The Washington Post in December 2021.

Michigan's 2002 anti-terrorism act defines terrorism as an act that is "intended to intimidate or coerce a civilian population or influence or affect the conduct of government or a unit of government through intimidation or coercion."

An attorney for Crumbley did not immediately respond to The Washington Post's request for comment.

In another rare move, the alleged shooter's parents were charged with four counts of involuntary manslaughter. James and Jennifer Crumbley face allegations that they ignored warning signs in their son's behavior and did not secure the gun their son used, which investigators alleged was stored in an unlocked drawer of their bedroom. They pleaded not guilty in 2021 and filed a motion in July to have the case against them thrown out, arguing that they never should have been charged because their son is the sole person responsible for killing four people.

At the time of the shooting in November 2021, it appeared to be the deadliest episode of on-campus violence in the United States in more than 18 months.