If you don't know the story of the Black Dahlia murder, you need to ask yourself this: Do I really WANT to know?

The reason that Los Angeles crime buffs still obsess over this unsolved murder after 59 years and the reason it still inspires books, movies, conspiracy theories and Web sites is this: The murder was so twisted, so bizarre, so savage, that once you've heard about it, you can't forget it.

Here is the sanitized version: On January 15, 1947, the body of 22-year-old aspiring actress Elizabeth Short was found in a vacant lot in Los Angeles. The body had been cleanly cut in half at the waist and drained of blood; she had been beaten and tortured, perhaps for several days, and her body was mutilated in unspeakable ways. If you must know more, there is plenty on the web; you can try lmharnisch.com or bethshort.com.

For tonight's story for AC360, we spoke at length to a retired LAPD detective who believes he has solved the crime, and has convinced a lot of people he is right.

Even that part of the story is twisted: Steve Hodel believes the killer was his father, a prominent doctor who died in 1999.

Hodel came to this conclusion only after the father died and left behind a small photo album containing two mysterious pictures, Hodel believes they depict Elizabeth Short. There is more: his father was trained in surgery; many believe it would have taken a surgeon to cut the body in half so cleanly, and his father's handwriting closely matches that on notes the police received in the 1940s from a main claiming to be the killer. The father's specialty was venereal disease, and because he treated LA's most prominent citizens, he was untouchable, just the kind of man who could get away with murder, the son says. He lays out his case in a widely praised book, 'Black Dahlia Avenger.'

When Hodel's book came out in paperback in 2004, James Ellroy who wrote 'The Black Dahlia' in 1987 said in the book's foreward, 'Now we know who killed her and why.'

But for reasons he won't now discuss, Ellroy has changed his mind, and made it clear he no longer endorses the Hodel theory. When I went to hear Ellroy speak in Los Angeles last week, he started his talk with these words of warning: 'One topic is forbidden: Who really killed Elizabeth Short. It's un-provable across the board. I will not discuss it under any circumstances.'