investigators wanted more from the witness. >> investigators but that person under hypnosis and use a sketch artists to draw a rendition of the person that she saw standing next to a car on daniels park road, which would have been 100 yards or so from where the body was found. >> that works. putting somebody under hypnosis? >> here's the thing, i've been in this business for 40 years and i heard where it worked and they've heard where it didn't work. >> the result was this sketch. was it the killer? and would it lead anywhere? >> coming up -- >> they're known as serial killers. and according to law enforcement officials, there are at least 35 of them roaming the country now. >> a chilling new possibility. >> i was even like, where was ted bundy at that time? we'll see in colorado? >> a string of notorious killers on the loose. could one of them have