From the Fortean Times’ Jonathan Dowd (link swiped from Boing Boing) :

In September 1944, a series of peculiar events rocked the town of Mattoon, Illinois. For almost two weeks, the town™s police department received dozens of reports from terrified residents that a mysterious prowler, dressed entirely in black, was haunting the streets and squirting anæsthetising gas into the faces of his victims. The reports got weirder. One described the mysterious felon as wearing a strange metal helmet or mask; another spoke of a Bigfoot-type creature.

Although the attacks petered out in mid-September, the events of that fortnight have since achieved near-mythical status. Like the incidents reported from London and Aldershot over half a century before, the real events that unfolded in Mattoon underwent a fortean sea change to become items of myth and folklore, and a local lunatic, more to be pitied than censured, became a figure of legend: if 19th-century London hatched ˜Spring-heeled Jack™, then 1940s Illinois gave birth to ˜The Mad Gasser of Mattoon™.

One fascinating aspect of these stories is that they provide some clues towards the workings of that peculiar sociocultural mechanism whereby real events become myths, one particularly prevalent in my own field of cryptozoology (most notably, perhaps, in the case of the exotic cats which now roam the wilder parts of the United Kingdom; they too have undergone this process, becoming the ˜Surrey Puma™, the ˜Fen Tiger™ or the ˜Beast of Exmoor™). The other thing we shouldn™t forget is that tales like those of the Mad Gasser of Mattoon are, quite simply, irresistible fun.