I was reading about Japanese urban legends on Wikipedia and found an American urban legend based on a true story regarding a man in a bunny suit:

The Bunny Man is an urban legend that probably originated from two incidents in Fairfax County, Virginia in 1970, but has been spread throughout the Washington D.C. area. There are many variations to the legend, but most involve a man wearing a rabbit costume ("bunny suit") who attacks people with an axe. Many variations occur around "Bunny Man Bridge", the concrete tunnel of a Southern Railway overpass on Colchester Road in Clifton.[1] Story variations include the origin of the Bunny Man, names, motives, weapons, victims, description of the bunny suit, and the possible death of the Bunny Man. In some accounts the Bunny Man's ghost or aging spectre is said to come out of his place of death each year on Halloween to commemorate his death. In some accounts, victims' bodies are mutilated.

Fairfax County Public Library Historian-Archivist Brian A. Conley has conducted extensive research on the Bunny Man legend. He has located two incidents of a man in a rabbit costume threatening people with an axe. The vandalism reports occurred a week apart in 1970 in Burke, Virginia.

The first incident was reported the evening of October 20, 1970 by USAFA Cadet Bob Bennett and his fiancée, Dusty, who were visiting relatives on Guinea Road in Burke. Around midnight, while returning from a football game, they parked their car in a field on Guinea Road to talk. As they sat in the front seat with the car running, they noticed something moving outside the rear window. Moments later the front passenger window was smashed and there was a white-clad figure standing near the broken window. Bennett turned the car around while the man screamed at them about trespassing, including "You're on private property and I have your tag number." As they drove down the road they discovered a hatchet on the car floor.

When the police asked for a description of the man, Bob insisted he was wearing a white suit with long bunny ears, but Dusty remembered something white and pointed like a Ku Klux Klan hood. They both remembered seeing his face clearly, but in the darkness they could not determine his race. The police returned the hatchet to Bennett after examination. Bennett was required to report the incident upon his return to the USAFA. It was later confirmed in Fairfax Police records that the man was wearing a bunny suit with ears instead, not Ku Klux Klan robes.[2]

The second reported sighting occurred on the evening of October 29, 1970, when construction security guard Paul Phillips approached a man standing on the porch of an unfinished home in Kings Park West on Guinea Road. Phillips said the man was wearing a gray, black, and white bunny suit and was about 20 years old, 5 feet 8 inches (1.73 m) tall, and weighed about 175 pounds (79 kg). The man began chopping at a porch post with a long-handled axe, saying "All you people trespass around here. If you don't get out of here, I'm going to bust you on the head." The man then ran into the woods.

The Fairfax County Police opened investigations into both incidents, but both were eventually closed for lack of evidence. In the weeks following the incidents, more than 50 people contacted the police claiming to have seen the "bunny man." Several newspapers reported the incidents, including the following articles in The Washington Post:

"Man in Bunny Suit Sought in Fairfax" (October 22, 1970)[3]
"The 'Rabbit' Reappears" (October 31, 1970)[3]
"Bunny Man Seen" (November 4, 1970)
"Bunny Reports Are Multiplying" (November 6, 1970)

In 1973, University of Maryland student Patricia Johnson submitted a research paper that chronicled precisely 54 variations on those two events.[4]

http://en.wikipedia.org/wiki/Bunny_Man