MONTEREY (CBS SF) — Charles Lafferty has pleaded guilty to 30 counts of felony assault stemming from a series of incidents that left six motorists injured when their vehicles were struck by projectiles, shattering windows, while traveling on Monterey and San Benito counties freeways.

Monterey County District Attorney Jeannine M. Pacioni announced that the 54-year-old Lafferty had pleaded guilty to 28 counts of assault with a deadly weapon and two counts of assault with a deadly weapon on a peace officer.

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The incidents involved Lafferty firing projectiles at numerous vehicles driving on South Bay highways between February 2019 and January 2020. He will receive a stipulated sentence of 15 years in state prison.

After Lafferty’s arrest, he admitted to repeatedly shooting marbles at traffic using a slingshot, but he never provided an exact number of times he did so. During his police interview, Lafferty did not disclose a motive for his actions.

Police seized a slingshot, a slingshot replacement band, and 55 marbles from Lafferty’s vehicle the day he was taken into custody.

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Lafferty was arrested in Nipomo on January 22, 2020 following a comprehensive investigation by the California Highway Patrol into more than 70 incidents of vehicles being struck with unknown objects while driving.

He became a suspect when his vehicle was identified at the scene of several incidents. A detailed digital forensic analysis linked Lafferty to more than 50 of the incidents reported to CHP. Some incidents were reported days or weeks after the fact, and not all drivers were able to provide the exact date, time, and location where their vehicles were damaged.

Six people in the affected vehicles suffered cuts and scrapes as a result of being hit with broken glass. A majority of the drivers and passengers were uninjured and no collisions were reported as a result of these incidents.

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The two counts of assault with a deadly weapon on a peace officer involved Lafferty shooting a marble at two CHP officers in a marked patrol vehicle who were responding to an earlier projectile incident. Neither officer suffered injuries.