WASECA — A southern Minnesota teenager accused of planning to kill his family and massacre students at his high school told police no one noticed he was mentally ill and that he had tried to hide his illness.

In newly released audio recordings of police interviews, the 17-year-old calmly described his plan to “dispose of” his family, set a fire as a diversion and use explosives and guns to attack his Waseca school. He said he thought it would be “fun” and that he was following his idol, Columbine gunman Eric Harris.

The teen is charged in juvenile court. He was arrested in April after authorities said they found him in a storage locker with bomb-making materials. His father said he doesn’t believe his son would have actually carried out the attack.