The Missing Piece

Between March and September of the year 1995, five murders shook the professional Speed Puzzle Tour. The modus operandi was always the same: the murderer would amputate the victim of a limb, then leave on the body a piece of a Polaroid photograph depicting the corresponding limb of another man. Evidently, speed puzzle, a sport by then as popular as football and basketball, had become the hunting ground of a serious killer.
Suspects are in no short supply: from the tyrannical president of the erudite Society of Puzzlology to the reigning champion who has mysteriously vanished to the billionaire who started the Tour.
Can you solve the puzzle?
The Missing Piece has been translated into a dozen languages.