The body of the six-year-old was found by her dad strangled in the basement of their family home in Boulder, Colorado, in the US, on December 25, 1996 just hours after a ransom note was left in the kitchen

JonBenet Ramsey was found dead in the family’s basement(Image: Daily Record)

Citizen investigators have urged police to retest DNA samples left at the scene to solve a decades old cold case of a murdered six-year-old beauty pageant star.

JonBenet Ramsey was found murdered just hours after a bizarre ransom note was left at her family house in Boulder, Colorado, in the US, on December 25, 1996.

According to an autopsy, she had been the victim of sexual abuse, with DNA samples found on her underwear and long johns.

The case received international attention and but more than 25 years on, no one has ever been convicted of her murder.

She had been strangled with a garrotte made from white rope and a broken paintbrush handle.

The family’s home in Boulder, Colorado, where the girl’s body was found (Image: Getty Images)

This was despite DNA being found at the scene which didn’t belong to anyone in the family.

Last year the Boulder Police Department announced a review of the case.

Now independent investigators, including a journalist who has covered the case for years and the daughter of a famous detective are urging police to retest any stored physical evidence for more DNA.

There are hopes any samples will be able to be tested against genealogy databases.

The girl dressed up in happier times(Image: Sipa/REX/Shutterstock)

The six-year-old had performed in children’s beauty pageants before(Image: Sipa/REX/Shutterstock)

Investigative journalist Paula Woodward covered the case when the girl’s body was first found and has published two books about it, reports The Sun.

She said: “The key will be the DNA evidence.

“I think there’s a good chance that the case will finally be solved if the right tests are done – JonBenét deserves some justice.”

In 1997, three months after the girl’s murder, the famous Colorado Springs detective Lou Smit was asked to come out of retirement to help with the case as a special investigator.

John and Patsy Ramsey, the parents of the murdered girl(Image: Denver Post via Getty Images)

In September 1998, he resigned from the case, saying: “They [Boulder police] have been going in the wrong direction and have been since day one of the investigation. Instead of letting the case tell them where to go, they have elected to follow a theory and let their theory direct them rather than allowing the evidence to direct them.”

Despite this Smit had a list of suspects and when he died in 2010 he passed this on to his family and former colleagues.

Now his daughter Cindy Marra and grandkids Lexi and Jessa are continuing the investigation.

Many suspected the parents of being involved but the DNA didn’t match(Image: Denver Post via Getty Images)

Lexi and Jessiva hosted a three-part podcast The Victim’s Shoes, which included their grandfather’s taped memos and case notes.

Writing in an email to Fabulous, Cindy said: “There’s a lot of physical evidence being held by Boulder Police Department.

“Some of it was sent in for testing, but some was not.

“Either way, it has not been tested, to our knowledge, since 2007.

If she had lived, JonBenet would be 32 now

“All of the physical evidence needs to be reviewed and sent to a cutting-edge lab, which has refined the process of extracting even minute quantities of DNA.

“Then, a genealogy expert could use this to search databases for possible suspects.”

The ransom note was considered unusual due to its length and the fact it asked for the exact amount the girl’s dad had received as a Christmas bonus the year before.