Many gamemasters lift plots from fiction for their games, as well as adapting real-life events into allegorical counterparts for their game worlds. This provides the advantage of having stories with a beginning, middle, and end, as well as locations and supporting characters. All you need to do to file the serial numbers off is change some the names of people and places. The disadvantage of using these types of tales in roleplaying games is that they come with he danger of railroading. Players tend to do gloriously unexpected things and don't tend to stick to the beats of a structured plot.
One solution to this is to use unsolved crimes as the basis for adventures. You have a plot, so basic beats, some characters and locations, but the ending is wide open for your players to write. You may even know who the villain is, but the player characters will need to build the case to prove it, and then catch the villain.
If you're running a modern or historical game, allowing the player characters to solve a real-world crime that's baffled the real-world authorities gives them a sense of prestige, and also establishes the alternate-reality nature of your game. It allows you to introduce the fantastic elements of your setting as explanations for the crime (Emelia Earhart? Well, she was flying over R'lyeh when she vanished). The crime might even have been solved, but the truth was so disturbing the general public must never know, or making the truth known would mean revealing the existence of things They don't want you to know about (cut to he final scene of Raiders of the Lost Ark).
The other advantage of using unsolved crimes as plot hooks is that they're cheap and easily available. You can find inexpensive books on unsolved crimes in used bookstores and in the bargain section of chain bookstores. Wikipedia is full of articles on unsolved crimes, and its reliability as an accurate research tool doesn't matter; if the facts are wrong, it can still make for a good adventure.
Have you ever used an unsolved true crime in your game? Share your thoughts in the comments below?