The 6-year-old pageant star was brutally murdered at her Colorado home on Christmas 1996. Her parents, brother and more have all been suspects, but to this day no one really knows who killed JonBenét.
O.J. Simpson was found guilty in a civil trial of both their murder's, but in the criminal trial the jury acquitted him. Technically, in the eyes of the law, the famous NFL player didn't do it, so their murderer remains unknown (and perhaps at large).
Depending on whom you ask, someone might say the legendary rapper is still alive. But the "Changes" rapper was murdered in 1996, and the investigation is still unsolved.
About a year and a half after Tupac, Biggie Smalls was shot four times in a drive-by shooting. His killer still remains unknown.
Casey Anthony, Caylee's mother, went through a highly public trial only to be found not guilty of her daughter's murder. As a result, it's still unknown who murdered this little girl.
Short, who was murdered in 1947, and the mystery surrounding her death became an instant media sensation. She received "The Black Dahlia" moniker posthumously, but to this day her killer remains unknown.
This couple was brutally murdered with an axe in 1892, but it was their daughter, Lizzie Borden, who was tried and acquitted for the crime. The deaths of Andrew and Abby Borden were never solved.
In 1888 an unknown serial killer hit the streets of London. More than 100 years later, the identity of Jack the Ripper remains unknown.
These murders were a series of poisoning deaths resulting from drug tampering in Chicago in 1982. The victims, which included children, had all taken Tylenol-branded acetaminophen capsules that had been laced with potassium cyanide. A total of seven people died in the original poisonings, with several more deaths in subsequent copycat crimes. The person responsible is still unknown.
He was a serial killer who acted in Northern California in the late 1960s an early 1970s, but his identity still remains unknown. The killer originated the name "Zodiac" in a series of taunting letters sent to the local Bay Area press. These letters included four cryptograms (or ciphers). Of the four cryptograms sent, only one has been definitively solved.