Kip Kinkel is led into Marion County Courthouse in 2007.

SALEM, Ore. — Twenty-five years after Kip Kinkel murdered his parents, killed two students and wounded 25 others in one of the earliest U.S. high-school shootings, lawyers have filed a new petition with the Oregon Supreme Court.

Kinkel opened fire at Thurston High School in Springfield, Oregon, in May 1998, at a time when America was unaccustomed to seeing such hateful mass violence directed at a school. Historians consider it to be a predecessor of sorts to the oncoming era of mass shootings in the U.S., many of which occur in schools, supermarkets and malls. The Columbine High School massacre occurred about a year later.

The night before the Thurston High School assault, Kinkel killed his parents, William and Faith Kinkel. His classmates, Ben Walker and Mikael Nicholauson, were fatally shot the next day at the school.