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On December 26, 1996, John Ramsey found his 6-year-old daughter JonBenét dead in the basement of their upscale home in Boulder, Colorado. His wife Patsy found a note that demanded a $118,000 ransom for JonBenét's safe return. The case became international news, thanks to photos and videos of JonBenét in child pageants.
Almost immediately, authorities focused on JonBenét's immediate family – her parents and her 9-year-old brother, Burke. Nearly three years after the murder, Burke was questioned by a grand jury, but never charged. In 2008 – two years after Patsy's death – prosecutors formally cleared both parents of any involvement in their daughter's death, citing unidentified third-party DNA at the scene.
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Eighteen-year-old Natalee Holloway vanished on May 30, 2005, during a high school graduation trip to Aruba. The night before she was supposed to leave the island, Holloway was seen by her classmates at a restaurant and nightclub. She was later seen in a car with Joran van der Sloot and two other men, who claimed that they had dropped Holloway off at her hotel.
Van der Sloot was arrested twice on suspicion of involvement, but was released each time due to lack of evidence. Van der Sloot would later make statements that many thought incriminated him, but he was never charged with a crime. Now 30, Van der Sloot is in a Peruvian jail for the murder of another woman, Stephany Florez Ramirez.
Holloway's body has never been found, and the investigation remains open.
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When Kyron Horman did not return home from Skyline Elementary School in Portland, Oregon, on June 4, 2010, police began a criminal investigation into the boy's whereabouts.
Kyron's stepmother, Terri Horman, told police she had brought the boy to school and stayed with him while he attended a science fair. She also stated that she left the school around 8:45 a.m. and remembered seeing Kyron walk down the hall toward his first class. But the school said he wasn't in class, and he was marked absent for the day.
A grand jury has met several times and continued to hear evidence in the case, but no indictments have been handed down.
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The 4-year-old British girl vanished on May 3, 2007, from her bed in a vacation apartment in Portugal. Madeleine's parents, Kate and Gerry McCann, left Madeleine and her two-year-old twin siblings asleep in the ground-floor apartment and dined with friends at a restaurant about 180 feet away. They told authorities that they checked on the children throughout the evening until Kate McCann discovered that the little girl was missing.
Over the past 10 years, authorities have investigated thousands of leads and pieces of evidence, but have not been able to determine what happened to Madeleine. Her whereabouts remain unknown.
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The 'Black Dahlia'
One of Hollywood's most notorious murder cases, 22-year-old actress Elizabeth Short – who the press posthumously dubbed "the Black Dahlia" -- was found dead on January 15, 1947. Her body had been cut in half and appeared to have been carefully drained of blood. The killer had also cut gashes into her face, leaving her with a clown-like smile.
Police worked in tandem with the media to disseminate clues and seek tips, but the tactic backfired: Several innocent people confessed to the crime. More than 70 years later, the case of the Black Dahlia is one of Hollywood's oldest unsolved murder cases.
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In 2006, 2-year-old Trenton Duckett vanished from his home in Leesburg, Florida. His mother, Melinda Duckett, told police that intruders had cut through a screen window after she had put her son to bed.
But as Melinda Duckett's story was called into question – and TV personalities like Nancy Grace began to criticize her – the 21-year-old mother shot herself to death with a rifle, saying in her suicide note that she was angry about being "faced with ridicule and criticism." Duckett's family sued Grace in 2006, and later settled for $200,000, which was put into a trust fund to help locate Trenton. He has never been found.
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On September 7, 1996, Tupac Shakur attended a Mike Tyson boxing match at the MGM Grand in Las Vegas. He got into the car of Suge Knight, the CEO of Death Row Records. At a stoplight, a white Caddilac pulled up next to the car and filed multiple rounds into Knight's vehicle. Shakur was rushed to a hospital where he died six days later from internal bleeding.
Although an entourage of about 10 automobiles were following Knight and Shakur's vehicle, witness accounts of the event varied. Several people claimed that Orlando Anderson had fired into the vehicle, but he was never charged and was killed less than two years later.
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Florida mom Michelle Parker vanished on November 17, 2011 – the same day the People's Court aired an episode in which she and her ex-fiance, Dale Smith, argued over a missing engagement ring.
Smith was one of the last people to see Parker, and court records documented the couple's lengthy history and Smith's conviction on a domestic violence offense. Investigators questioned him several times, but never charged him with a crime in Parker's disappearance. Parker's vehicle was abandoned in a parking lot in an Orlando apartment complex, and her phone was later discovered in a lake, but the 33-year-old woman has never been found.
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The Zodiac Killer
In the late 1960s, a serial killer terrorized San Francisco residents, killing at least 5 people, but maybe dozens more. The spree began in December of 1968, when a young couple was shot to death sitting in their car. Over the next 10 months, the killer shot a couple in a public park, stabbed another couple sitting by a lake, and executed a cab driver with a gunshot wound to the head.
The killer toyed with police and the media, calling in several of the murders to police. He sent coded letters to newspapers and police in which he called himself "the Zodiac" and claimed to have killed 37 people.
"I like killing people because it is so much fun," he wrote in one letter. Authorities have only been able to definitively tie him to 5 murders and 2 attempted murders. Nearly five decades later, the case remains a mystery.
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On May 11, 2011, Illinois mom Amy Fry-Pitzen told administrators at Greenman Elementary School that she had a family emergency, and that she'd need to take home her 6-year-old son, Timmothy. The boy hasn't been seen since.
Three days later, Fry-Pitzen's body was found in a hotel room in Rockford, Illinois. She had slashed her own wrists and neck. A note was found that said that her son was safe with people who would love and care for him. "You'll never find him," read the last line of the note.
Despite a nationwide search and pleas from the boy's father, Jim Pitzen, Timmothy is still missing.
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Character actress Barbara Colby worked steadily in the early 1970s, with roles on The Odd Couple and Gunsmoke, before landing a recurring role on The Mary Tyler Moore show and its spinoff, Phyllis.
On July 24, 1975, Colby and an acting colleague, James Kiernan, were walking to their car following an acting class when they were shot by two unidentified assailants. Colby was killed instantly, but Kiernan was able to describe the shooting to police before he, too, died. Kiernan told cops that there was no attempt to rob the pair, and that he didn't know why they were targeted.
Despite Kiernan's description, police have never identified the killers and the case remains open.
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The Jamison Family
In October 2009, Bobby and Sherilyn Jamison and their 6-year-old daughter Madyson mysteriously vanished in southeast Oklahoma. Their abandoned truck was found near their home. There had been no signs of a struggle. Inside the vehicle were the couple's wallets, phones, and $32,000 in cash. The family dog, Maizy, was also in the car, malnourished from not having eaten in several days.
Four years later, their skeletal remains were found just three miles away, lying face down and side-by-side in the woods. Due to decomposition, the Medical Examiner was unable to determine a cause or manner of death for the trio.