WASECA — Prosecutors appealing the dismissal of the most serious charges leveled against a 17-year-old boy accused of plotting a school attack said the judge’s decision has had a critical impact on the case.

In their appeal of the judge’s decision in late July to drop half of the 12 charges, prosecutors said the counts that were dismissed were the only ones that could have presumably carried a prison sentence and affect whether the teen is moved to adult court, reports said.

Waseca County Judge Gerald Wolf dismissed four counts of attempted murder and two counts of attempted damage to property. Wolf said prosecutors didn’t show sufficient evidence that the boy had made “a substantial step, beyond mere preparation,” to commit murder or property damage.

The judge allowed six counts of possession of explosives to stand.

Prosecutors outlined in the appeal the steps they claim the teen took to bring his plot to fruition. They included getting a job and opening a bank account to acquire explosives, buying an arsenal of ammunition firearms and powders, buying ball bearings and a pressure cooker, renting storage space to assemble the devices and detonating multiple devices on school grounds, prosecutors said. They also asked the judge for an opportunity to make oral arguments.

The teen was arrested in April after authorities said they found him with bomb-making materials in a storage locker in Waseca, 70 miles south of Minneapolis.

Court documents say police also found guns, explosives and a 180-page journal that outlined a plan to kill his family, set a fire to divert first responders, then go to Waseca Junior and Senior High School and “kill as many students as he could.”