SALEM, OREGON -- Kip Kinkel, who killed his parents before going on a shooting rampage at his Oregon high school in 1998, killing two classmates and injuring 25 more, has given his first news interview, telling HuffPost he feels "tremendous, tremendous shame and guilt."

Kinkel, now 38, is serving a de facto life sentence at the Oregon State Correctional Institution. He spoke with the news site by phone for about 20 hours over 10 months.

He said he felt guilty not just for what he did as a 15-year-old suffering from then-undiagnosed paranoid schizophrenia, but the effect his crime has had on other juvenile offenders sentenced to life terms: His case has been held up by some of his victims and by others as a reason to oppose juvenile justice reform in the state.

While he has not previously given interviews because he did not want to further traumatize his victims, he said, he also began to feel that his silence was preventing those offenders from getting a second chance.

"I have responsibility for the harm that I caused when I was 15," Kinkel said. "But I also have responsibility for the harm that I am causing now as I'm 38 because of what I did at 15."

FILE - This undated file photo provided by the Oregon Department of Corrections shows Kipland Kinkel.

Kinkel described how he had been hearing voices since age 12 and how he became obsessed with knives, guns and explosives, believing China was going to invade the U.S. and that the government and the Walt Disney Co. had implanted a microchip in his head.

When he was caught at Thurston High School in Springfield with a stolen handgun he bought from another student on May 19, 1998, "My whole world blew up," he said. "All the feelings of safety and security - of being able to take control over a threat - disappeared."

Facing expulsion, a possible felony charge and an enormous sense of shame, he said, the voices in his head made him believe he had to kill his parents and then return to school to "kill everybody."

He killed his parents the next day, and the day after that he opened fire in the school cafeteria, killing 16-year-old Ben Walker and 17-year-old Mikael Nickolauson and injuring 25 before being subdued by other students.

He pleaded guilty - at the time, he did not want to accept his diagnosis and felt community pressure to resolve the case rather than plead not guilty by reason of insanity. He was sentenced to nearly 112 years after apologizing profusely.

"I feel tremendous, tremendous shame and guilt for what I did," he told HuffPost. "I hate the violence that I'm guilty of."

Kinkel shot Betina Lynn in the back and foot. She told HuffPost the idea of him ever getting out is "literally terrifying." She has permanent nerve damage, a constant reminder of what happened.

"Even now, more than 23 years later, I and many other survivors are still dealing with the fallout," Lynn said. "We are all serving life sentences right alongside him."

Kinkel described how he underwent mental health treatment at the youth prison where he began his sentence and recognized he harmed innocent people, including his parents, whom he loved. He also said he cried when he learned about the 1999 massacre at Columbine High School in Colorado, afraid that he had inspired it.

Fighting his sentence

Kinkel, who has obtained a college degree behind bars, continues to challenge his sentence, which was upheld by the state Supreme Court. In March, his attorneys filed a petition in federal court, arguing that his plea was not voluntary - he had been off his meds for several weeks beforehand - and that his sentence was unconstitutional.

"Sentencing a juvenile to die in prison because they suffer from a mental illness is a violation of the Eighth Amendment," his lawyers wrote.

In 2019, as part of a national effort to reevaluate tough-on-crime sentences for juveniles, the Oregon Legislature passed a measure to stop automatically referring 15- to 17-year-olds to adult court for certain offenses and to ensure that they weren't sentenced to life in prison without a chance to seek parole. At the time, there were about a dozen people serving life or life-equivalent terms for crimes committed as juveniles.

But critics warned that that the measure could lead to Kinkel's release, and a month later, lawmakers passed another bill to make clear that the measure was not retroactive.

"It doesn't matter if he was 15," Adam Walker, the brother of Kinkel's victim Ben Walker, said in a video released at the time. "The victims don't get second chances. Why should the offenders?"

Kinkel said he watched the debate in the prison library.

"It was like, there was hope," Kinkel said. "And then the Legislature ... came back and said, 'No, we are specifically, intentionally, purposely with everything that we have, going to take this away from the kids already in the system.'"

He said he doesn't often consider the possibility of ever being released: "I don't allow myself to spend too much time thinking about that because I think that can actually bring more suffering."