After retiring from his career in Mexican revolutionary politics, Villa retired to an estate along with a sizable force of bodyguards. Despite this, he was taken out by a rooftop gunner in what appeared to be a planned hit, while driving down the street. One theory claims it was an estranged bodyguard, but we’ll probably never know for sure.

B. H. DeLay was a prominent stunt pilot of the era, but died during a show after the wings of his plane folded in a stunt. The crash killed him, and his passenger, President of Essandee corporation R.I. Short. An investigation revealed that the plane had been sabotaged, and DeLay reported that he had been shot at a few days prior. But nobody knows who wanted DeLay dead.

Casper Holstein was a prominent New York mobster, and made much of his money running an illegal lottery. However, he was briefly kidnapped for three days by five white men and held for a ransom of $50,000. After he was released, he refused to identify his kidnappers, even though he claimed he could, and that the ransom wasn’t paid. Holstein took the identity of his kidnappers to the grave.

In 1926, the Hartselle Bank in Alabama was robbed just after nightfall, when anywhere from five to 15 men blasted open the safe, and waltzed off with some serious cash. Although a few suspects were later arrested for unrelated crimes, there were no arrests made, and the full criminal crew was never uncovered.

The truth behind Virginia Rappe’s death, and actor Roscoe "Fatty" Arbuckle’s subsequent trial, will likely never be uncovered. While the two were at a party together, Arbuckle claimed he found her vomiting, and in discomfort. Three days later, Rappe was taken to the hospital, and died after complications from a ruptured gallbladder. However, Rappe’s friends claimed the actor assaulted her at the party, and Rappe herself allegedly stated, “he did this.” Arbuckle was found innocent.

One of the most infamous moments of the decade occurred when over 40 people were killed in a bombing outside of the Wall Street Stock Exchange. Although the "American Anarchist Fighters" were blamed, there wasn’t enough evidence to convict anybody, and nobody fessed up to the crime.

Peter Verigin was a Doukhobor community leader in Canada, who died in a train explosion. But while the Russian exile’s pacifist and holistic community had many enemies, it was never uncovered whether the explosion was an accident, or a targeted attack.

In 1924, Ed Nichols, Roy Wilson, and Dewey Morris were found dead near their cabin in Little Lava Lake, Oregon. But the prime suspect Charles Kimzey evaded capture for multiple years, and when he was found, there was not enough evidence for a conviction. Thus, the Lava Lake murders remain unsolved.

After an alleged argument with her husband, Agatha Christie left her house, and her car was found abandoned. However, after she was reported missing, the mystery writer popped up 11 days later at a spa. She claimed to have amnesia, and while her whereabouts might have officially been a mystery, we’re willing to bet she knew exactly what she was doing.

Glen and Bessie Hyde were a newly married couple on their honeymoon on the Colorado River rapids, when they went missing. Although drowning seems the most likely fate, their boat was found intact, with no signs of a turnover, and with all supplies available on deck.

Ince was a prominent silent film figure, who died three days after leaving his own birthday dinner on Mogul William Randolph Hearst’s yacht early, in discomfort. While heart failure was listed as the official cause, rumors spread that Hearst had discovered Charlie Chaplain fooling around with Marion Davies at the party, and accidentally shot Ince, intending to hit Chaplain. Ince was cremated, so there is no way to know.

Check out our tell-all on Hearst’s iconic California mansion.