Mount Diablo and Z's transformation into a concerned citizen
I have been interested in the fact that Z changes his focus from close-up lover's lane murders to bombs threats and Mount Diablo in 1970-71. This is the period when "Save Mount Diablo" is established, in response to development threats in the area. The transformation from occultish slave collecting killer is complete by 1974 (if one accepts those letters), when Z becomes a moralizing concerned citizen. Looking at this evolution, it is hard not to think of TK.