I always thought this sounded like some idea Zodiac was behind and manipulated these guys into doing this. IMO
All the threats of getting school children and Busses…
http://www.trutv.com/library/crime/gang … index.html
One of the guys is out and on Facebook. 
https://www.facebook.com/richard.schoenfeld.31
“…they may be dealing with one or more ersatz Zodiacs–other psychotics eager to get into the act, or perhaps even other murderers eager to lay their crimes at the real Zodiac’s doorstep.“ L.A. Times, 1969
A good article about them.
http://news.google.com/newspapers?nid=1 … 749,910212
A quarry, junk cars….does sound Zodiac-ish….just way to young.
“…they may be dealing with one or more ersatz Zodiacs–other psychotics eager to get into the act, or perhaps even other murderers eager to lay their crimes at the real Zodiac’s doorstep.“ L.A. Times, 1969
