JonBenét Ramsey's Father Is Optimistic DNA Advances Will Catch Daughter's Killer, Slams Boulder Police

More than 25 years after the grisly murder of JonBenét Ramsey, the little girl's killer remains at large.

JonBenét, a 6-year-old decorated, pageant princess, was found sexually assaulted, beaten and strangled to death in the cellar of her affluent Boulder, Colo., home, Dec. 26, 1996.

No one has ever been charged with her murder.

In the new Tubi/Fox Alternative Entertainment crime documentary Suburban Nightmare: JonBenét Ramsey, her father John Ramsey calls on police to release never-before-seen DNA evidence to allow for broader testing from outside entities, in hopes of finally putting his daughter's murder case to rest and her killer behind bars.

"This was an evil, sick person," John, 79, tells PEOPLE.

John says the FBI speculated the person responsible for JonBenét's death "was either very angry" or "very jealous" of him. "This had nothing to do with JonBenét," he says. "It was a heavy burden to hear."

"There were times for a long time after JonBenét was killed that I wanted to die. The pain was so intense," admits John.

But despite the decades that have passed and the grief he's had to live with, John remains hopeful now more than ever that advances in DNA technology, coupled with the dismissal of one of her case's lead detectives, justice will prevail in a case that has left authorities perplexed for so long.

"That was a huge removal of a roadblock to getting things done," John says of the ousting of Cmdr. Thomas Trujillo. "With him out of the way, I think there's some hope that things will change."

According to a Boulder Police Department news release earlier this month, Trujillo was forced to transfer to another division after an internal investigation revealed cases assigned to him between 2019 and 2022 "had not been investigated or investigated fully."

He also received a three-day suspension and was placed on a Performance Improvement Plan, the release reads.

John says Trujillo oversaw JonBenét's case from the start, but the release made no mention of her 1996 case specifically.

John has long been vocal about the Boulder police's handling of his daughter's case, arguing their investigative methods were rigid and narrow-minded, and the crime scene was improperly preserved by investigators at the time.

"The city is not commenting on the ongoing JonBenet Ramsey case at this time," The BPD tells PEOPLE. "I can confirm that Cmdr. Tom Trujillo has been transferred to Patrol and is no longer involved in investigations, including this particular case. The reason for his transfer was not related in any way to the Ramsey case."

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In November, police announced they would be consulting with the Colorado Cold Case Review Team to reexamine JonBenét's case.

With a seemingly revitalized interest from investigators, John remains optimistic that the unidentified male DNA collected from JonBenét's clothing, if tested, will result in a match against a familial DNA database and the arrest of his daughter's murderer.

"I'm pretty confident that's going to yield some results," John says. "But we don't know until we try. We know there's more that can be done."

Boulder police considered John and his wife Patsy Ramsey primary suspects early in the investigation, but John maintains the couple's innocence.

Patsy died from ovarian cancer in 2006. The Ramseys were publicly exonerated two years later.

"They made their decision on who was guilty on day one ... well before they even got crime scene evidence," John says. "And I think they just said, 'Well, it's always the parents.' That was the whole strategy to solve the case. It wasn't to look at it openly."

With decades behind him since JonBenét's ruthless killing, John is pleading for justice, and for the perpetrator to spend the rest of his life in prison.

"I just want him identified," he says. "I've gone past the stage of 'just put me in the room with him and we won't need a trial' to 'how do I forgive somebody like this?' as the Bible says we must do. I wrestled with that for several years. But I want to know why. Why did he do this?"