I checked this out on Snopes.com to see if it was an urban legend but it is true. I quote:
Origins: We have no way of telling if this is an "actual true story and not one of those Internet stories that are passed on and on" -- the details given in the account aren't sufficient to assist us in confirming the tale, and searches through online news databases based on what little is included (that the incident happened in Virginia in the last week of December 2001) don't fetch any articles about an arrest made or charges laid in such a case. And some of the details in the story give us pause: Why didn't the fleeing woman speed up, flash her lights, or honk her horn to attract the attention of the police car in front of her? And how did the real police car fail to notice the warning lights of the phony, unmarked police car?
Whether this particular tale is true or not, women driving alone have been sexually assaulted by rapists pretending to be police officers, so the advice it gives (to not pull over in deserted areas when signaled to do so by an unmarked police vehicle) is well worth heeding. Keep driving until you get to a well-lit area where there are others about. Call 911 and tell them what's happening. (Although in at least in some U.S. states, #77 on a cell phone will immediately connect you to that state's highway patrol, that code is not universal. Some states use #77, but others use *55, *47, or *HP, and some don't have any special code at all. Rather than frantically try to figure out which one will work in the area you're in, get around the problem by going straight to 911.)
The instance of rapists and murderers pretending to be police officers is not of epidemic proportions, but enough incidents of this nature have occurred that precautions are warranted.
In 1948 in Los Angeles, Caryl Chessman successfully robbed couples and sexually assaulted a number of women in California after first fooling them into believing he was a police officer by flashing a red light at their vehicles. (Though often he approached parked cars this way, in at least one case he managed to pull over a car that was driving on Pacific Coast Highway.) His method of approach earned him the nickname of "The Red Light Bandit." Chessman was executed on a kidnapping charge in 1960, but only after gaining fame for writing three books while in prison (most notably Cell 2455 Death Row) and becoming the focus of the then nascent movement to abolish the death penalty.
Since then others have used similar ruses to isolate their victims. More recently, in 1997 Arkansas was plagued by its "blue light rapist" who assaulted three women after first luring them to the side of the road with the help of a police-style blue light mounted on his car. Robert Todd Burmingham was sentenced in 1998 to 80 years in prison for rape, kidnapping, and aggravated robbery.
In 2000, a Tampa woman was sexually assaulted by a man who had put a flashing blue and red light atop his car and motioned her off the road as if he was a police officer. After she admitted she had been drinking, he offered to drive her home; she got into his car, and he took her to an isolated location where he raped her. That case is still open.
Someone who has taken to impersonating a police officer for nefarious purposes is counting upon his intended victim's unquestioning cooperation. Because he appears in the guise of a trusted authority figure whose commands must be obeyed, he expects automatic reaction to kick in even if it overrides common sense. That could prove a fatal error to make.
In 1996 Governor Pataki issued an executive order to prevent unmarked New York state police cars from stopping motorists for routine traffic violations, citing "a growing number of cases around the country in which criminals trap their victims by posing as police officers." If he's worried about it, you should be too.
Barbara "worry thwart" Mikkelson
Last updated: 29 April 2002
The URL for this page is http://www.snopes.com/horrors/mayhem/fakecop.htm