As I understand it (based on a dim memory of some sixth grade memorization, and a quick glance at Wikipedia) the sixth and fourteenth amendments to the constitution guarantee Americans a fair trial. But one of our local serial killers already had a fair trial, and it turned out really badly. Even though he was showing off the body of his victim, the jury believed his story, "She was already dead when I found her and started bragging about killing her."
Now his attorney wants to throw out evidence in his latest trial for torturing and killing a different woman. I don't think so. We did that once, and look what happened.