In the early 1980s, over a period of about two to three years, the Green River Killer murdered 50 women or more near Seattle and Tacoma, Washington. During this time, Gary Leon Ridgway was briefly a suspect, and he was given a polygraph test. The test, done in 1984, determined that he was telling the truth about his innocence. He was free to keep killing, and he did.You can Try this out on http://www.liedetector.uk Site
In 2001, DNA evidence (and other evidence) proved that he was the killer. In 2003 he pleaded guilty to 48 of the murders. Meanwhile, Melvin Foster, a taxi driver who had also been a suspect in the case, had taken the polygraph test in 1982. He failed — the test indicated he was lying, although police could not gather enough evidence to arrest or prosecute him. Of course, this lack of evidence was due to the fact that he was innocent.
Unfortunately, Foster was under a cloud of suspicion for almost 20 years. Gary Ridgway’s confession, and the DNA evidence, finally exonerated him. According to an article in the King County Journal, in 2003 Foster asked for the King County Sheriff’s Office “to apologize and return his rock tumbler and all the rest of the stuff police took from his home in 1982.”
It would be nice to think that this doesn’t happen often, but how do we know? There are certainly many other stories about innocent people pointed at as guilty due to a failed polygraph, but we only know about the ones where the truth comes out. Had Ridgway not been caught, many would still think Melvin Foster was guilty.
Why is this explained to you (if it is)? Because hearing how this works actually makes you more susceptible to the anticipatory build-up of tension, and the measurable “relief” once you answer. It also makes you more of a believer in the polygraph test itself.