On the day after Christmas in 1996, John and Patsy Ramsey woke up to discover that their 6-year-old daughter, JonBenét, a child beauty queen, was missing from the family’s home in Boulder, Colorado.

A handwritten ransom note demanding $118,000 (John’s exact bonus that year) was found on the stairs near the kitchen. Seven hours later, John discovered his daughter’s lifeless body in a small room in the basement.

The case has captivated the nation for decades.

Now, 28 years later, John Ramsey remains hopeful that his daughter’s killer will be caught. He believes new DNA technology can help police re-investigate JonBenét’s murder, a case that attracted worldwide attention.

JonBenet’s autopsy revealed that she had been sexually assaulted and strangled, and that her skull had been fractured. Unknown DNA was found under her fingernails and in her underwear.

The Ramseys quickly became suspects, even though there was no evidence linking them to the crime.

The Ramseys have consistently maintained that they were not involved in JonBenet’s murder. However, it took twelve years for the Boulder District Attorney’s Office to fully acquit the Ramseys and their son Burke.

As the weeks passed with no arrests made in the case, a media frenzy began to build, fueled by non-stop tabloid images of JonBenét competing in beauty pageants.

A number of suspects emerged, including a man named John Mark Karr, who confessed to the murder in 2006. However, his DNA did not match the evidence, so he was never charged. The case remained open.

To this day, John Ramsey believes there is a cloud hanging over his family because there are still people in the country who believe he and his late wife Patsy, who died in 2006, are responsible for JonBenét’s murder.

“There would still be 5 to 10% of the population who think, ‘Yes, it was the father or yes, it was the mother,'” John said.

Despite the loss of his wife and daughter, John Ramsey remains steadfast. He has now remarried and finds comfort with his children and grandchildren.

John is also working with director Joe Berlinger on a new docuseries streaming on Netflix titled “Cold Case: Who Killed JonBenet Ramsey?”

“We believe the crime can be solved,” Berlinger said. “We want to put pressure on the Boulder Police Department to do DNA testing.”

The docuseries recaps the early stages of the investigation. From the start, there were questions about how the police handled the investigation.

“Early on, they explored the crazy idea that the parents were responsible,” Berlinger said. “They get tunnel vision, so they don’t want to explore all the possibilities.”

The crime scene is also being closely monitored because it may have been contaminated, which Berlinger said posed additional challenges.

People flowed through the house, from the kitchen to the living room.

Boulder police told “Nightline”: “We are committed to following up on every lead. We will continue to work with DNA experts and our law enforcement partners across the country until this tragic case is solved. This investigation will always remain a priority for the Boulder Police Department.”

John Ramsey is convinced that advances in DNA technology can help identify his daughter’s killer.

“A number of old cold cases have been solved using this genealogical research,” John Ramsey said. “Let’s do a reverse family tree and see if he (the killer) had a relative living in Boulder in 1996. That’s what we’re asking the police to do.”