We're always interested in compelling true crime stories, but the best ones leave us with more questions than answers.
These 10 unsolved crimes are a great puzzle for your imagination, if you don't mind some grizzly stories. We may never know the truth about them, but there are still cash rewards waiting to be claimed for most of these cases.
10. D.B. Cooper
In 1971, a man using the alias Don or "D.B." Cooper bought a one-way airline ticket to Seattle. Once the plane was in the air, he claimed he had explosives in his suitcase and hijacked the plane.
After ordering the pilots to land, Cooper was given $200,000 by police, then ordered the plane to take off again. He finally jumped out of the plane - with a parachute and the money - somewhere between Seattle and Reno.
While a handful of clues have turned up, after interviewing more than 1,000 suspects the FBI's file on the Cooper skyjacking is still open.
9. The Long Island Serial Killer
By chance, an officer training his canine partner in 2010 discovered a woman's body dumped beside Long Island's Ocean Parkway. The body was stuffed in a burlap sack, and within two days police found three more just like it.
Authorities soon realized they had a serial killer on their hands, but they've never identified the man suspect of murdering as many as 16 women over almost two decades. The killer is also known as the "Craigslist Ripper" for his habit of targeting escorts on the popular website.
The $25,000 reward for information that puts this killer behind bars is still unclaimed.
8. The Gardner Museum Robbery
In the early hours of March 18, 1990, two police officers responded to a distress call at Boston's Isabella Stewart Gardner Museum. After museum guards let the men inside, they revealed themselves to be thieves in disguise.
After handcuffing the guards, the thieves walked out with 13 pieces of art worth a combined $500,000, making the heist the most valuable theft of private property ever.
Last year, the museum offered a $10 million reward for information about the heist, but there's still no sign of the two robbers or any of the art.
7. The Black Dahlia
Actress Elizabeth Short was found murdered in 1947, with her body dumped in a vacant lot outside Los Angeles. Police were stunned to find Short's body had been cut in half, and had its blood drained out before it was dumped.
While more than 150 suspects were interviewed - and some even turned themselves in - no one was ever arrested for Short's murder.
6. The 300 Million Yen Robbery
On December 10, 1968, four employees of a Japanese bank were traveling through Tokyo in a company car loaded with 300,000 million Japanese yen. The huge load of bank money and employee bonuses would be worth $5.7 million today.
A police officer on a motorcycle warned the men their car had been strapped with a bomb, which fit with threatening letters the bank had received days earlier. The officer tried to disarm the bomb under the car, but smoke and flames started pouring out from underneath it.
As the bank employees ran for cover, the fake police officer drove away with their money. The bomb scare was part of the robber's plan, and no trace of the money was ever found.