Otto,I took a polygraph many years ago,but it wasn't for a crime--it was just pre-employment screening--but it was very important to me at the time--it was for working as a burglar alarm monitor--it was actually a second job that I needed desperately--They hooked me up,I was nervous as hell,but I still passed it just fine--so I certainly believe in them,they work 80% of the time--I think that by volunteeering to take one,volunteering,you are already showing the police you are anxious to prove your innocence,and if its a false positive--so what? its inadmissable in court--they cannot even mention it in court--they need evidence to nail you--of course there are famous examples of guilty passing it,the green river killer for one--but if you are innocent,you would never hesitate to take it,because they actually need evidence to just bringyou to trial,let alone to convict you