Who Killed Arlis Perry?

Arlis Kay Perry was a newly married nineteen-year-old when she entered Stanford Memorial Church at Stanford University in the late night hours of October 12th, 1974. She would be found the next morning, the victim of a brutal murder in what appeared to be a ritualistic killing.
Her case has remained unsolved for the past forty-two years. Various rumors and theories abound as to who her murderer was. There is conjecture that she was the victim of the Son of Sam, the Zodiac Killer, the Death Angels and the Process Church.
The police never obtained solid leads on her case and it remains as much a mystery today as it was over forty years ago.
Who killed Arlis Perry?