(CNN) -- John David LaDue readily admits he came from a good home and says he was never bullied.
But something in him drove the 17-year-old Minnesotan toward an obsessively detailed plot -- one in which, he said, he wanted to kill his family, set off bombs at a school and then shoot students.
"I think I'm really mentally ill," he told police. "And no one has noticed. I've been trying to hide it."
Transcripts of LaDue's police interviews were released Tuesday. They fill more than 140 pages.
And they offer, in his own words, a chilling glimpse of a teenage boy and his homicidal mindset -- and how far he had wanted to go to act on it.
LaDue was arrested in April before he could carry out his attack. He sits in jail facing numerous charges, including attempted murder. He has pleaded not guilty.
CNN does not usually publish the names of minors charged with crimes but is naming LaDue in this case because his name has been widely reported in his community.
LaDue's mother told police she had no idea he was allegedly plotting to kill his family.
Yet, he said, he plotted right under her nose. He made no effort to hide anything. He told police they'd find three live bombs in a box on the floor next to his bed.
LaDue said his main target was Waseca Junior/Senior High School. But first, he said, he was going to kill his father, mother and sister.
"They did nothing wrong; I just wanted as many victims as possible," he told officers who questioned him.
He had a low opinion of Lanza, he said, because he shot small children.
"I didn't want to be known as a guy who would go to a place with a bunch of kindergartner(s)," he told police. He thought it more honorable to kill students his own age.
LaDue had studied mass killers in the United States dating back to the 1920s and rated them on the intensity of their crimes, he said.
He had a pecking order of killers he admired. One of his favorites used explosives to kill people at a school.
After slaying his family, the teen, who idealized the Columbine school shooters in particular, allegedly wanted to set a fire.
The arson, however, would only be a diversion to tie up emergency responders while he carried out the main plot at the school, police said.
He'd planned to set off "numerous bombs" during the lunch hour at Waseca Junior/Senior High School, then kill the school resource officer.
Then he'd shoot at students until police officers arrived. He wanted to die but thought it cowardly to turn the gun on himself the way Lanza did.
"I wanted to get taken down by the SWAT," he told officers, according to the newly released documents. "I really wanted to get out of this place."
Luckily, a witness thwarted his plan when she saw the 17-year-old tending to a storage locker, where he kept his stash of bomb-making materials.
She dialed 911.
Officers arrived to find LaDue in the locker surrounded by an assortment of gunpowder, pyrotechnic chemicals, ball bearings and a pressure cooker, police said.
LaDue asked his interviewers to let him see a psychiatrist over his state of mind.
In the eighth grade, he was a model student, whose report card was filled with top grades, he said.
A year later, his thoughts began to turn dark.
"I started having homicidal ... thoughts about some people in my school," he told officers.
He loved his chemistry class in particular and developed a fascination for explosives. Recipes to concoct the volatile chemicals were right at his fingertips.
"I spent hours, maybe hours a day reading websites of how to synthesize things like mercury fulminate and nitrocellulose, HMX, HNB and various other things," he said.
His mother described how she'd go to bed and see him still in front of his computer screen, but she had no idea what he was up to.
LaDue built bombs, starting off with small charges. Police found videos he made of himself setting off his homemade devices.
He tested them then tinkered with their designs to improve them, he said.
A close call
The teen's cache in the storage locker contained just pieces of the puzzle.
Police got a search warrant in April and went to LaDue's home, where he lived with his family.
Behind that door lay finished bombs, "numerous guns" and ammunition, police say. And they found LaDue's neatly laid plan in a journal dozens of pages thick.
A bomb squad removed all recovered explosives and destroyed them by controlled detonation at a local airport.
They did so just in time. Everything was prepared and ready to go; LaDue was just waiting for the right moment to launch the scheme.
A lucky calendar this year may have prevented him from hatching his plan earlier -- before it could be thwarted.
He had wanted to carry it out on April 19, a day before the 15th anniversary of the mass shooting at Columbine High School in Colorado. The date fell on a day when school was out.
"But then I had to skip it," he said. "I wanted it to be in April, because it's my favorite month ... because that's the month that all the really bad tragedies happened."
CNN's Ric Ward, Cristy Lenz and Emma Lacy-Bordeaux contributed to this report.