Although "The Mothman Prophecies" claims to be based on real events, there's relatively little about the incidents which inspired John A Keel's book of the same name.
While the film sees John Klein (Keel/Klein - see what they've done there?) chasing an enigma around modern day West Virginia, the legend of the Mothman actually began in 1966.
A young couple driving in Point Pleasant, West Virginia saw a huge, winged creature with red glowing eyes. Petrified, they sped on, the creature flying behind them at an estimated 100mph, making a screeching noise, before disappearing.
This was one of several numerous sightings of the so-called Mothman and for a year weird things continued to happen in the area - lights in the sky, UFO sightings, visits from strange, unearthly 'men in black' who questioned inhabitants, mysterious phones calls, unexplained electrical problems, and over 100 Mothman sightings. Local man Woody Derenberger also claimed to receive prophesies from a being named Indrid Cole, but these were never investigated and Derenberger became a figure of ridicule.
The media descended on the town but no explanation could be found for the disturbances. Then in December 1967 a tragedy ended the sightings. On December 15, the 700 ft Silver Bridge linking Point Pleasant with Ohio collapsed suddenly, spilling heavy Christmas traffic into the Ohio river, killing 46 people. (No policewomen or reporters went into the water, mind.)
None of the events were linked - apart from in theories. Some think the Mothman was simply a Tyto Alba barn owl, others reckon that the events were caused by a Native American curse. Most popular of all, that Point Pleasant was a 'window' for alien activity and the Mothman was warning of disaster.