It is a fantastic analysis of the area of Presidio Heights, with respect to the options Zodiac faced that night as he walked away from the intersection of Washington and Cherry. Of course, it was around 10:00 pm at night when the Zodiac Killer departed the crime scene, and the route ahead of him was far more claustrophobic.
With photographs showing the layout of Presidio park, Rex comes to the conclusion that Zodiac most likely headed east from Julius Khan playground to the dense wooded area by Presidio Boulevard.
The Zodiac Killer, now waiting for an opportune moment, had just a few hundred feet to escape the Presidio to his waiting vehicle.
The killer would now reach his vehicle, parked somewhere close to Broadway and the Lyon Street Steps. A relatively remote area for residential San Francisco and an ideal location to escape to Highway 101 and the Golden Gate Bridge in a matter of minutes.
You are now out of San Francisco and away.