I don't know whether you've ever read that strange whodunit book by Stephen King, The Colorado Kid, but I do it quite regularly. At least once a half of a year I take it from the shelf, blow the dust off of it and try to solve that impossible mystery once again.
The same is true for Gerry Feltus, an Australian policist in retirement, or Nick Pelling, a British encoding specialist, do roughly the same thing with roughly the same non-existent success chances.
The mystery they both are trying to solve is the identity of the so-called Somerton Man. This obscure man was found dead on beach in Adelaide, Australia, back in 1948 and since then being the Holy Grail of many criminalists' generation. The reason for their interest lies in the fact that so far there have been few (well, practically no) clues that could help identify him or even the cause of his death. The only hint at what might happen before he died can be a large amount of blood in his stomach that the police experts discovered during the autopsy. However, any further indications of his death being violent, neither wounds, nor traces of any poison, could be confirmed. Moreover, there were absolutely no hint at who the dead man could be either: not a single document, even all of his lables were removed out of his clothes so he could not be identifed even in this way.
Several years later, a scrap of paper with the mysterious words 'Tamam Shud' and a sequence of letters that looked much like a code was found in the dead man's clothes. It was found out that the scrap was torn out of a highly rare edition of Omar Khayyam, with the book thrown into the car standing nearby the place where the body was discovered.
Well, I don't knwo whether you've really got interested in the case, but if you have you should check out the Wikipedia article about it. It's awesome.