(NewsNation) — Netflix's "Cold Case: Who Killed JonBenét Ramsey" director and executive producer Joe Berlinger is calling on the Boulder Police Department to communicate with the Ramsey family and run new DNA testing.
"There's unidentified DNA mixed with JonBenét's DNA, and it's a terrible sample," Berlinger said on "Elizabeth Vargas Reports." "There's been amazing advances in DNA technology, but let them do this testing. We still don't know if they've (Boulder police) done anything."
No one has ever been charged in the case, though multiple suspects have been investigated over the years.
Police in Boulder, Colorado, previously said there are fresh leads in the decades-old cold case, and they believe it is possible they will find out who killed 6-year-old JonBenét Ramsey.
Police Chief Stephen Redfearn released a video in response to Berlinger's docuseries and noted there are aspects of the case that can’t be discussed publicly.
“What I can tell you, though, is that we have thoroughly investigated multiple people identified as suspects throughout the years, and we continue to be open-minded about what occurred as we investigate the tips that come into detectives,” he said. “I can also tell you that detectives are regularly investigating some aspects of this terrible crime, and I receive updates frequently.”
John and Patsy Ramsey reported their daughter missing on Dec. 26, 1996, telling police they found a ransom note in the house. She was found dead several hours later, in the basement of the family’s home, having been beaten and strangled.
At the time, the case gained attention in part because JonBenét competed in child beauty pageants. Videos and photos of the pageants included some that many people found to be suggestive in nature.
Police and media focused on John and Patsy Ramsey as suspects initially, though other theories included an intruder who had entered the home, possibly while the family was out celebrating Christmas.
John Ramsey believes genetic genealogy could help track down his daughter’s killer.
NewsNation's Brian Entin contributed to this report.
