The Zodiac Killer's response was almost immediate, when he hand delivered the 'Debut of Zodiac' letter just one day later, on August 4th 1969 to the San Francisco Examiner, to leave you in no doubt he was replying directly to Jack E. Stiltz. The Zodiac's opening gambit was "In answer to your asking for more details about the good times I have had in Vallejo, I shall be very happy to supply even more material. By the way, are the police having a good time with the code? If not, tell them to cheer up; when they do crack it, they will have me". He went on to describe the Blue Rock Springs Park and Lake Herman Road attacks in much greater detail and effectively informed Jack E. Stiltz about his attached gun sight; "What I did was tape a small pencel flash light to the barrel of my gun. If you notice, in the center of the beam of light if you aim it at a wall or ceiling you will see a black or darck spot in the center of the circle of light about 3 to 6 inches across. When taped to a gun barrel, the bullet will strike in the center of the black dot in the light. All I had to do was spray them as if it was a water hose; there was no need to use the gun sights. I was not happy to see that I did not get front page coverage".
Fast forward to Presidio Heights on October 11th 1969 and Chief Inspector Martin Lee's claims that Zodiac "has made some mistakes." They did not believe that Zodiac could have been hiding in the park. Chief Inspector Martin Lee stated "His boast of being in the area we were searching is a lie. We had the whole area flooded with lights. We had seven police dogs and a large number of patrolmen searching the area tree by tree and bush by bush. The dogs are the best in the country. A mouse couldn't have escaped our attention."They also irked the Zodiac by claiming he had left fingerprints on the interior and exterior of the taxicab, particularly the blooded fingerprints on the driver side door panel.
Zodiac again felt compelled to reply in the November 9th 1969 'Bus Bomb' letter: "I have grown rather angry with the police for their telling lies about me...... p.s. 2 cops pulled a goof abot 3 min after I left the cab. I was walking down the hill to the park when this cop car pulled up + one of them called me over + asked if I saw anyone acting suspicious or strange in the last 5 to 10 min + I said yes there was this man who was runnig by waveing a gun & the cops peeled rubber + went around the corner as I directed them + I disappeared into the park a block + a half away never to be seen again", and again asked for newspaper coverage similar to the 'Debut of Zodiac' letter by threatening more attacks: "By the way it could be rather messy if you try to bluff me. PS. Be shure to print the part I marked out on page 3 or I shall do my thing. To prove that I am the Zodiac, Ask the Vallejo cop about my electric gun sight which I used to start my collecting of slaves".
The last time the Zodiac Killer was doubted, he supplied extra details of the Blue Rock Springs and Lake Herman Road attacks to Vallejo Police Chief Jack E. Stiltz, including his "small pencel flash light". He would repeat this in the Bus Bomb Letter, reminding everybody that he most certainly was the Zodiac Killer. In other words, to not doubt him and "Ask the Vallejo cop about my electric gun sight which I used to start my collecting of slaves". The Vallejo cop he is referring to, is Jack E. Stiltz. The Vallejo cop, to which he sent details about his improvised gun sight in the 'Debut of Zodiac' letter only three months earlier. He proved to Jack E. Stiltz that he was both the letter writer and the killer, and again here, in the Bus Bomb letter, he is referring back to this Vallejo cop - and to not doubt him again.