John LaDue arrived Monday morning.

The Waseca County attorney’s office on Monday is expected to seek adult charges against a 17-year-old Waseca High junior who told police he planned to set off bombs and go on a shooting spree at his school.

John David LaDue, who police say outlined his plot in chilling detail — and backed it up with a cache of guns and homemade explosives — is currently charged as a juvenile with four counts of attempted murder, two counts of first-degree damage to property and six counts of possession of a bomb by someone under 18.

If convicted of one count of first-degree attempted murder as an adult, LaDue could serve up to 18 years in prison, according to state guidelines. If convicted as a juvenile of the same offense, LaDue could be released from juvenile detention when he turns 21.