In my purely unprofessional opinion, of the 4 Zodiac-attributed attacks, the Stine murder would seem like the one most likely to be solved: eyewitnesses, possible fingerprints, evidence taken from scene, etc. How did the letter writer know this crime would not be solved and thereby perpetuate the zodiac story? Yes, I realize this question contains an assumption on my part. Yet, the letter writer invested heavily in the Stine murder and in fact wrote multiple letters on the topic - as if he knew the whole thing wouldn't blow open and reveal the unconnected crimes (if connected only by hoaxing). The fact that not one of the crimes was solved or the origin of the letters discovered is bothersome. If so many people were involved, one would think that at least one part of the truth would be revealed by someone directly involved.