A former suspect in the JonBenét Ramsey murder case admitted to killing the child by "accident" in 1996.

According to the Denver Post, convicted pedophile Gary Oliva made the confession in a series of disturbing letters sent to his former classmate Michael Vail. He detailed his obsession with the six-year-old, who was found murdered inside her family's Boulder, Colorado home.

"I never loved anyone like I did JonBenét and yet I let her slip and her head bashed in half and I watched her die," Oliva wrote. "It was an accident. Please believe me. She was not like the other kids."

At the time of the murder, the 54-year-old was a registered sex offender whose address was listed near the Ramsey's residence; but according to Rolling Stone, Oliva wasn't considered a suspect until 2000, when he was arrested on unrelated charges. Upon his arrest, authorities discovered a number of suspicious items in his possession, including a picture of JonBenét and a poem he'd written titled Ode to JonBenét. He was cleared in the case after investigators found that his DNA didn't match evidence at the scene.

Oliva is now serving time for a 2016 child porn case, in which he was convicted of possession 22 separate sexually explicit images of children under the age of 10. He is up for parole next year. 

Boulder authorities dismissed the man's confession, stating investigators have already ruled him out as the suspect.

"The Boulder Police Department is aware of Mr. Oliva and has investigated his potential involvement in this case, including several previous confessions," Boulder police wrote in a statement. "The department routinely receives information on this investigation. Information provided to the police department is reviewed along with the many tips and theories we receive. There are no new updates in this investigation and the department will not comment further."

JonBenét was found dead in her family's basement in December 1996. A suspect has never been charged in the case and the investigation is remains open.