John LaDue first harbored thoughts about killing people around the eighth grade.

"Not thinking about it seriously like I was now," he told police on the April night they found him in a storage unit with bomb-making materials. "Just, like, entertaining the thought."

In audio recordings of his initial police interviews, released Tuesday by the state court office, the 17-year-old is heard calmly and precisely describing his plans to first "dispose of" his family because he wanted as many victims as possible, set a fire in the country for a diversion and then carry out a massacre at the junior and senior high school in Waseca, Minn.

He offered varying explanations over the course of his hourslong talks with officers, according to the recordings and transcripts.

"I think I'm just really mentally ill and no one's noticed and I've been trying to hide it," he said initially, adding that he'd never been bullied and has good parents. He wanted to "get out of this place," he said.

Later, he told an officer he thought it would be "fun" and he would be following his idol, Columbine gunman Eric Harris.

Several times, LaDue told police that he wanted to see a psychiatrist. He'd wanted to ask many times, he said, but didn't want his parents to know because he feared getting treatment would mean "I might not think the same way I do now and I might not get my goal done."

After police foiled his plan anyway, he said, it didn't matter anymore. "I just want to find out what's wrong with me, actually," he said.

Carefully mixing explosives

LaDue's voice cracked at times, including when he told a Waseca officer about thoughts he'd had about killing another student who had annoyed him.

When LaDue detailed his process for making bombs, his voice grew more confident, speaking precisely in describing the chemistry involved and the safety precautions he'd take in mixing explosives.

LaDue described studying websites and buying materials online with money from his job and cash he stole from his parents' wallets.

When his father had questions about ball bearings that had arrived in the mail — which he planned to use as shrapnel in a pressure cooker he had bought on sale at Wal-Mart — LaDue said he was using it for "some high-definition CD audio."

He didn't have a list of students he was targeting, he said. "I would have taken anyone out, I didn't care."

He said, though, that he wanted to kill older students, not seventh-graders. He didn't want to be known like Sandy Hook shooter Adam Lanza, who killed young elementary school children, he said. "That's just pathetic," he told an officer. "Have some dignity."

LaDue preferred shooters who operated under the radar: "Someone you'd say, 'I never knew he would do something like that.' Someone you would not suspect."

LaDue is 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. Prosecutors are trying to have him charged as an adult.

He said several times in police interviews that no one knew about his plot, nobody knew what he was thinking.

LaDue's parents hadn't seen the transcripts or heard the audio Tuesday night, his father said. David LaDue said earlier, though, that he doesn't believe his son would have ever carried out his plot and that the teens needs help, not punishment.

Practicing

A smart kid who made A's and B's in school, LaDue was fascinated by guns and explosives. He would spend hours reading websites about how to synthesize explosives at home and gradually moved up to building his own small improvised explosive devices and detonating them all over town, at a playground, a church, at the gun range, on school grounds.

His YouTube channel was full of videos of his experiments, including one explosion of a small bomb made of toilet bowl cleaner, aluminum foil and an apple juice bottle.

A couple of friends helped him detonate some small explosives. He was testing the friends, he admitted, observing how they reacted to some things that he showed them, trying to gauge them as potential partners for his plan. "I wanted a partner really badly, but I observed many of my friends, and I could tell that none of them would do it, so I didn't ask the question of any of them," he said.

Preparing to carry out his plan alone, LaDue told officers he planned to use two pressure cooker bombs with explosives three times more powerful than the ones used at the 2013 Boston Marathon.

"I thought three casualties was pretty lame," he said. He had enough explosives for one pressure cooker, he said, to "spread you from here to Owatonna, basically."

He'd planned to put one pressure cooker inside a recycling bin and detonate it at the second lunch shift, when a lot of students were around. He would detonate a second bomb, he said, when students were fleeing. Then he would throw Molotov cocktails and pipe bombs, and "when the SWAT comes I would destroy myself," he said.

LaDue said he'd started thinking about his specific plan more than a year earlier and detailing it in a notebook he kept locked in his room.

Bombs and ammunition

LaDue told investigators that counselors at school never suspected he was mentally ill. Nor did his parents or other family members, according to affidavits of detectives in the case also released Tuesday.

Jodi Kubat, LaDue's manager at the Hy-Vee, described him as a "quiet and respectful kid," who used to hang around the store when he wasn't working. Once, she said, another cashier found him standing alone in a darkened room at the store, at 10 p.m. on a night he wasn't working.

Police were tipped off to LaDue in late April after a 911 caller thought someone was breaking into the MiniMax Storage Units in Waseca. When police arrived, unit #129 looked more like a living space than a storage unit, with furniture and lanterns, the affidavits said.

LaDue's desktop computer was running when officers searched his bedroom. A search of the "favorites" and his recent search history showed a string of sites with instructions on bombmaking and other sites where he had purchased chemicals to manufacture explosive devices, police said.

LaDue's uncle John Leslie LaDue seemed dumbfounded by the charges. "You know, I'm not a religious man, but I'm telling you, I keep praying that somebody's gonna find a god damn brain tumor in his head," he told investigators. "I want an explanation. … I want to know, what, where was this fork in the road? What, what, what happened?"

pam.louwagie@startribune.com 612-673-7102

jennifer.brooks@startribune.com 612-673-4008