An appeals court has rejected an attempt to overturn the most serious of the criminal convictions resulting from a mass shooting at Oxford High School in Michigan, according to court documents filed Tuesday.

The Michigan Court of Appeals denied Ethan Crumbley’s request to appeal his life sentence, citing a "lack of merit in the grounds presented."

Ethan Crumbley, sentenced to life in prison for killing 4 students, had his request turned down by the Court of Appeals.