It has been almost 30 years since the death of child beauty pageant queen JonBenét Ramsey, but the case remains unsolved.

The six-year-old girl was found dead in the basement of her family home in Boulder, Colorado on 26 December, 1996.

Despite numerous investigations and court cases, no one has ever been found guilty of her murder.

Channel 5 will be airing a two-hour long documentary Who Killed JonBenet Ramsey? A Suburban Nightmare on Thursday 26 September at 10pm, which explores the unsolved crime with unprecedented access to her father John, who is still pushing for answers to the identity of her killer.

Here’s what we know about JonBenét Ramsey and those associated with the case.

Who was JonBenét Ramsey?

Born on 6 August, 1990 in Atlanta, Georgia, JonBenét had already garnered a number of beauty pageant titles before her death including America’s Royal Miss, Colorado State All-Star Kids Cover Girl, Little Miss Charlevoix Michigan and Little Miss Colorado.

Her mother Patricia (Patsy) Ramsey was a former beauty pageant veteran.

Early on the morning of 26 December 1996, her family had reported the six-year-old missing to police after discovering a ransom note.

The note demanded a payment of $118,000 from JonBenét’s father, John Ramsey, otherwise his daughter would be killed.

Businessman John Ramsey was the president of Access Graphics, a computer software company, at the time and the sum in the ransom note was identical to his Christmas bonus.

An initial search of the house by police did not locate JonBenét’s body and Mr Ramsey began making arrangements to pay the ransom.

However, during a second search of the house at lunchtime the same day Mr Ramsey found his daughter’s body in one of the rooms in the basement.

Her mouth had been covered in duct tape, a white nylon cord was tied around her wrists and neck and her body had been covered by a white blanket.

A post-mortem later revealed she had died from asphyxiation due to strangulation. She also had a fracture to her skull and evidence suggested she may have been sexually assaulted.

Her death was ruled to be homicide and the case remains open, with an ongoing investigation.

She was buried in Marietta, Georgia on 31 December, next to her half-sister from her father’s first marriage, Elizabeth Pasch Ramsey, who had died in a traffic collision several years earlier.

Her mother, Patsy Ramsey, died of ovarian cancer in 2006 and was interred next to her daughter.

John Ramsey wed for a third time in 2011 to Jan Rousseaux.

Who might have killed JonBenét Ramsey?

There have been two main theories surrounding responsibility for the death of JonBenét Ramsey – the first involves her family, and the second an intruder – as well as several theorised perpetrators.

The Ramsey family were heavily scrutinised during the initial investigation for a few reasons, while there were several pieces of physical evidence to support the theory that an intruder had broken into the Ramsey home and killed JonBenét – including a boot print found next to her body which did not belong to anyone in the family, DNA from an unknown male found on her underwear, and a broken window in the basement believed to be a likely point of entry.

John, Patsy and Burke Ramsey

Among the reasons that investigators looked into JonBenét’s family were questions over the ransom note.

Police reportedly felt the note may have been staged as it was unusually long, written using a pen and paper from the Ramsey house, and demanded a sum of money matching that which John Ramsey had recently received as a bonus – raising suspicions that it was written by someone who knew the family well.

All three members of JonBenét’s immediate family – her parents, John and Patsy, and her brother Burke, who was nine years old at the time – were questioned by investigators and submitted handwriting samples.

John and Burke were both cleared of any suspicion of having written the note, and while Patsy could not be conclusively cleared by her handwriting sample, there was a lack of other evidence to support the theory that she had written it either.

The Ramseys were also reportedly reluctant to cooperate with police, but later said this was because they feared they would be targeted as easy subjects and that the authorities would therefore not conduct a full investigation.

In 1999, a Colorado grand jury voted to indict the Ramseys on charges of child endangerment and obstruction of a murder investigation, but the prosecutor felt the evidence did not meet the standard of being beyond a reasonable doubt and therefore declined to prosecute.

JonBenét’s parents and brother were never officially named as suspects in the murder.

Meanwhile, what was believed to be pineapple was found in JonBenét’s stomach by the coroner, and there was a bowl of pineapple in the kitchen which had Burke’s fingerprints on it.

The Ramseys maintained that Burke was asleep in his room all night, and there was no physical evidence to reflect otherwise, but a 2016 CBS documentary titled The Case of: JonBenét Ramsey appeared to imply he was the killer, theorising that he had hit his sister in the head with a heavy object after she stole a piece of pineapple from his bowl and that the ransom letter was an attempt to cover up the circumstances of her death.

Burke filed a $750m (£560m) lawsuit against CBS for defamation, with the case settled and “amicably resolved to the satisfaction of all parties” in 2019.

John Mark Karr

Among the possible suspects over the years was school teacher John Mark Karr, who was arrested in Thailand in August 2006 after confessing to JonBenét’s murder.

He claimed to have drugged JonBenét before sexually assaulting and accidentally killing her, but this was later ruled to be a false confession when authorities could not find any evidence linking him to the crime scene.

Karr reportedly provided only basic, publicly known facts in his confession.

JonBenét’s autopsy did not indicate the presence of any drugs in her body, while Karr’s DNA did not match samples found at the scene and police could not confirm he was even in Boulder at the time.

Gary Oliva

In 2019, convicted sex offender Gary Oliva seemingly confessed to the murder, claiming in a series of letters and poems to have killed the six-year-old by “accident.”

Oliva, who at the time was in prison on child pornography charges, sent the letters to his former school classmate Michael Vail, writing in one that he “never loved anyone like I did JonBenét” and that he “let her slip, and her head bashed in half, and I watched her die.

He added: “It was an accident. Please believe me. She was not like the other kids.”

Vail also claims he received a phone call from Oliva on the day JonBenét’s body was found, saying he “just hurt a little girl”. Oliva’s former classmate said he informed police in Boulder of that call but it was reportedly not followed up on by investigators.

When Oliva was arrested on a drug charge four years later, a photo of JonBenét was found in his possession, but he was cleared of the murder as his DNA samples did not match those found at the crime scene.

Oliva had previously been arrested for sexually abusing a young girl in Oregon in 1990, and then spent more than a year in jail for attempting to murder his own mother by strangling her with a telephone cord.

After his release, he moved to Colorado and was reportedly a drifter in the Boulder area, including near the Ramsey family home at the time of JonBenét’s murder.

Upon his 2016 arrest for uploading child pornography, he was found to have hundreds of images of and related to JonBenét, including photos of her autopsy.

When Vail received the letters containing the apparent confessions three years later, he alerted the authorities in Boulder and also released them to the public. Handwriting experts were commissioned by a private investigator, and last year reportedly found similarities between Oliva’s handwriting and the ransom note discovered inside the Ramsey home.

One of the experts told The Sun: “When you overlay some of those letters and words – words and letters from different eras of writing – and they line up so well, that’s a clear indication in my profession.”

Despite the recent developments, Oliva – who was released from prison earlier this year – has never faced charges relating to the case, with a Boulder Police spokesperson saying the department was “aware of and has investigated Mr. Oliva’s potential involvement in this case” but would “not comment on any actions or the status of this investigation.”

A message on a webpage for the case on the website BoulderColorado.gov says: “We continue to investigate and encourage anyone with any information to contact detectives at BouldersMostWanted@bouldercolorado.gov“.