The Zodiac Killer had struck in the Bay Area four times, so what was the likelihood he would now bypass this area and other closer cities and make the 150 mile round trip to Modesto from Vallejo (assuming he lived there or close by). This was the first time the Zodiac Killer was publicly challenged by a murder victim's famiy member, drawing ire from investigators and some people in Modesto towards Joe Stine for effectively enticing the killer into their midst - and we know how Zodiac rose to being challenged or questioned in the newspapers. If we believe the account of Kathleen Johns, the next time the Zodiac would resurface would be in Modesto exactly 5 months later. If this abduction was the work of the Bay Area murderer, was this simply a coincidence or had the Zodiac Killer chosen Modesto deliberately to add to the frustrations of law enforcement and bring condemnation upon the brother of Paul Stine?
If the Zodiac Killer lived in the Bay Area, would he really travel this distance late at night solely for the purpose of disabling a woman's vehicle and taking her on a trip around Tracy for upwards of two hours, unless it was important to strike fear into the people of Modesto in a wilful and deliberate choice on his part? After the challenge by Joe Stine on October 22nd 1969, two communications would arrive at the San Francisco Chronicle. The first contained the hidden message of Paradice and Slaves, along with By Gun, By Rope, By Knife and By Fire clockwise in each quadrant, effectively mimicking the Halloween card that would arrive nearly one year later. The second correspondence opened with the words "This is the Zodiac speaking up to the end of Oct I have killed 7 people. I have grown rather angry with the police for their telling lies about me. So I shall change the way the collecting of slaves. I shall no longer announce to anyone. When I committ my murders, they shall look like routine robberies, killings of anger, + a few fake accidents, etc".
The Zodiac Killer had already completed his attacks using a gun, rope and knife in that order, so what were the odds that his next attack after the challenge by Joe Stine would be in Modesto, use fire as part of the crime and attempt to imitate a fake accident, thereby changing his way of collecting slaves. The answer may have come five months later on March 22nd 1970, when the abductor of Kathleen Johns took her into nearby Tracy, but inexplicably headed back towards Modesto before she escaped into a field along Highway 132. Then for some unexplained reason decided to set fire to her vehicle, even though there seemed no purpose in doing so. If the Zodiac Killer had deposited any fingerprints on her vehicle by "snapping off the lights, and pocketing the keys" as Robert Graysmith claimed in his book, then it was a far easier task to just wipe down the couple of places he touched. Setting fire to her vehicle by the side of Highway 132 to extinguish fingerprints was totally unnecessary, unless of course, the Zodiac Killer wanted to satisfy the "by fire" element in his agenda.
Did the Zodiac Killer pick up the trail of Kathleen Johns in Modesto as she passed near the area where Joe Stine worked at the Richfield Service Station at 706 Sutter Avenue? Her journey along Highway 99, before turning west onto Highway 132, would have taken her only 4,750 feet from the Richfield Service Station. If this were the case, then we have the challenge laid down by Joe Stine in Modesto, followed by two communications that included "by fire" and "fake accidents", with the Zodiac Killer turning up in Modesto within one mile of the Richfield Service Station and subsequently disabling Kathleen Johns vehicle before setting it on fire. Does such a departure from his previous crimes pour doubt on this as a Zodiac attack, or is the Modesto connection reason enough to forge a viable fifth attack into the hands of the Bay Area murderer?