I was not sure where to post this, so I just put it in the Welcome section. You can move it, if there is a better place.
Tom Voigt has a video on YouTube (just him talking, nothing to see) where he talks about the possibility of the Zodiac being a police officer, but he doesn't mention Ray or Dennis Land.
Murder Basement #4 -->
I know you two do not like each other, but I think it is worth listening to. He mentions that one of the Police Departments were on strike, and the Zodiac threat may have been to scare the public. You might find something useful in that talk.