August 30, 1982 - Kip Kinkel

On May 21, 1998, 15-year-old freshman student Kipland "Kip" Kinkel opened fire with a semi-automatic rifle in the cafeteria of Thurston High School in Springfield, Oregon, United States, killing two of his classmates and wounding 25 others. The day before, he killed his parents at the family home, following his suspension pending an expulsion hearing after he admitted to school officials that he was keeping a stolen handgun in his locker.

During the year before the shooting, Kinkel displayed increasingly aberrant behavior and a heightened fascination with weapons and death, leading his parents to take him to a psychologist, who diagnosed Kinkel with major depressive disorder. Kinkel's parents had not disclosed any histories of mental illness in their families, and Kinkel himself had not told anyone about having heard voices urging him to violence since he was 12, out of fear of being ostracized or institutionalized. After the shooting, Kinkel pled guilty to murder and attempted murder and was sentenced to 111 years in prison without the possibility of parole; a sentence upheld on appeal. He was additionally diagnosed with paranoid schizophrenia and began taking antipsychotic medication.

Content sourced from en.wikipedia.org/wiki/1998 Thurston High School shooting under CC BY-SA 4.0.