SALINAS, Calif. (AP) — A man who pleaded guilty to using a slingshot and glass marbles to randomly attack dozens of vehicles on two Northern California highways, shattering their windows and frightening drivers, has been sentenced to 15 years in prison.

KSBW-TV reports 54-year-old Charles Lafferty received the sentenced Tuesday as part of a plea deal he reached in April in which he agreed to plead guilty to 30 counts of assault with a deadly weapon.

The California Highway Patrol investigated nearly 70 attacks that started in February 2019 and continued until shortly before Lafferty’s arrest on January 22, 2020.

Officials said Lafferty attacked drivers traveling in the opposite direction of his truck.