In the police reports about the Blue Rock Springs attack it states that at 12:10 am Vallejo police dispatcher Nancy Slover takes a call from a female that says that two juveniles were being shot at “at Blue Rock Springs parking lot.”

Then at 12:40 the killer calls and says:

“I want to report a double murder. If you go one mile east on Columbus Parkway to the public park you will find kids in a brown car. They were shot with a 9-millimeter Luger. I also killed those kids last year. Good-Bye.”

What we can observe: When the killer says “…if you go one mile east on Columbus Parkway to the public park….” he is describing the location of the bodies but is not familiar with it. He does not say the name of the park, he says “public park.” When he says “if you go one mile east…” he is giving directions to the scene–directions for someone driving via Interstate 80.

I wanted to test this idea as best I could, so I used the directions tool on Google Maps. Of course, the roads are somewhat different in 2024 than they were in 1969, but I verified that most major freeways and streets were indeed in existence then

If you ask for directions to the Blue Rock crime scene from downtown Vallejo, it routes you out Springs Road to Columbus Parkway, and then north to the park. I tried it from various spots around Vallejo, the downtown, the police station, the location of Darlene’s house, and it always gave me this result. In no case did it route me on to I- 80.

But once you start from locations outside of Vallejo, like San Francisco, and Oakland from the south, Fairfield and Sacramento from the north, it routes you on Interstate 80 and has you exit at Columbus Parkway and head east 1.7 miles.

Given that the Zodiac did not use the name of Blue Rock Springs Park, and that he uses the directions coming from I-80, I think it is most likely he did not live in Vallejo.

I think it much more likely that Zodiac was a resident of San Francisco, at least by some point in 1969, because he measured himself against the San Francisco Police Department. In his letters he often ended with a scorecard: SFPD – 0 Zodiac – 13, and the like. In the “Exorcist” letter of January 27, 1974, the letter concludes: Me – 37 SFPD – 0. He was really fixated on the San Francisco Police Department. Not the Solano or Napa County Sheriff departments, not the Vallejo Police Department, not the FBI nor California State Police. Zodiac kept score against the San Francisco Police Department. I conjecture that is so because that is where he lived.