> up next, a vibrant real estate professional is brutally murdered. >> this involved the entire range of violence. >> even hardened professionals are troubled by what they see. >> for there to be that much blood left at a scene, that's what we consider overkill. >> police find a possible witness and try hypnosis to get every detail. >> how many times do you see a composite sketch and you're like, this looks like every human being on the face of the planet? >> it was a real whodunit. and i hate whodunits. >> the killer leaves behind a clue, but will it be enough? >> people will kill for the most trivial of reasons. on a hot summer day, a married couple decided to look at a sample home in a ranch housing development in mckinney, texas. when they walked into the sample home, they couldn't find the sales associate. but they knew right away that something was wrong. >> and they walked into the