On the morning of January 15, 1947, a mother taking her child for a walk in a Los Angeles neighborhood stumbled upon a gruesome sight: the body of a young naked woman sliced clean in half at the waist.

The body was just a few feet from the sidewalk and posed in such a way that the mother reportedly thought it was a mannequin at first glance. Despite the extensive mutilation and cuts on the body, there wasn't a drop of blood at the scene, indicating that the young woman had been killed elsewhere.

The ensuing investigation was led by the L.A. police department. The FBI was asked to help, and it quickly identified the body—just 56 minutes, in fact, after getting blurred fingerprints via "soundphoto" (a primitive fax machine used by news services) from Los Angeles.

The young woman turned out to be a 22-year-old hollywood hopeful named Elizabeth Short—later dubbed the "black dahlia" by the press for her rumored penchant for sheer black clothes and for the Blue Dahlia movie out at that time.

Short's prints actually appeared twice in the FBI's massive collection (more than 100 million were on file at the time)—first, because she had applied for a job as a clerk at the commissary of the army's camp cooke in California in january 1943; second, because she had been arrested by the Santa Barbara Police for underage drinking seven months later. The Bureau also had her "mug shot" in its files and provided it to the press.

In support of L.A. police, the FBI ran records checks on potential suspects and conducted interviews across the nation. Based on early suspicions that the murderer may have had skills in dissection because the body was so cleanly cut, agents were also asked to check out a group of students at the University of Southern California Medical School. And, in a tantalizing potential break in the case, the Bureau searched for a match to fingerprints found on an anonymous letter that may have been sent to authorities by the killer, but the prints weren't in FBI files.

Who killed the black dahlia and why? It's a mystery. The murderer has never been found, and given how much time has passed, probably never will be. The legend grows...