WASECA — A judge on Monday dismissed the most serious charges against a 17-year-old boy accused of plotting to kill his family and attack his southern Minnesota school.

Waseca County Judge Gerald Wolf dismissed four counts of attempted murder and two counts of attempted damage to property.

Wolf said in his ruling that 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.

Defense attorney Dawn Johnson told The Associated Press that her team is pleased the judge made “the legally correct decision in a controversial case.”

Messages left for prosecutor Brenda Miller at her office after hours and at her home were not immediately returned Monday evening.

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 they 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.”