I've noticed that in addition to the instance of Kathleen Johns' purported escape from the Zodiac Killer, there have been some other famous cases in which would-be victims of serial murderers have found the good fortune to elude the malevolent intentions of the killer in their midst.. I happened to catch a documentary about the Green River Killer and was impressed by the story surrounding Rebecca Garde Guay: "In 1984, Rebecca Garde Guay actually came forward to police to say that she had been assaulted two years prior by a man who tried to kill her with a chokehold. Not only did Guay know Ridgway's place of employment (he had shown her an identification card), but she also picked him out of a book of photos. What's worse, Ridgway had the sheer gall to admit having "dated" Guay and even choking her."
The parallel here with Kathleen Johns' situation vis-a-vis the Zodiac Killer case is to me quite striking. Johns, too, got away from her abductor. Some years later Johns went on to state with great conviction that her captor was Zodiac suspect Lawrence Kane. For assorted reasons, however, just as with Ridgway in the Green River case, Kane was casually evaluated and ultimately exonerated of suspicion by law enforcement authorities.
In another, although perhaps slightly less credible, example (the story was sold to a tabloid publication), there is a woman named Mary Willis who allegedly slipped the grasp of the BTK killer in 1981. She reported the incident to police but nothing came of it. When BTK was arrested more than 20 years later, Willis was positive this was the man who had nearly taken her life.
Another notable correlation between the now solved Green River murders and the still open Zodiac case concerns the matter of suspect evaluation. In the early years of Green River, a man by the name of Melvin Foster became the chief suspect of homicide detectives. Foster even failed a lie detector he was administered and had his house searched searched twice by police. One of the initial signals that tipped-off police about Foster as a strong suspect was his desire to "help" with solving the case. The FBI has long maintained that serial killers will frequently volunteer their services to authorities to aid in their own capture. This very same rationale was applied to the Zodiac case when prime suspect Arthur Leigh Allen politely offered to assist the SFPD with their investigations after he'd been questioned. That he did so was one of the principal reasons law enforcement continued their dogged efforts at finding a way of connecting Allen to the Zodiac murders--a pursuit which, like Foster, included searches of Allen residencies, as well as his submission to a polygraph test. Allen passed his test.
In conclusion, it's often been the consensus opinion that the Zodiac Killer is most likely a person who has never come under the radar of law enforcement and is doubtful to be any of the known suspects. A counterpoint to this argument takes the form of Green River Killer, Gary Ridgway. Ridgway had long been a suspect--and a cleared one, at that--before forensic evidence eventually caught up with him and proved his guilt. In light of such knowledge, there is sound reason to believe the Zodiac Killer needn't be an elusive mystery man hidden beneath the earth, but could very well be one of the select few public suspects we've looked at hundreds of times. The key, as always, is in the forensics. By having DNA tested only one popular suspect, Allen, a massive disservice is being done toward the goal of closing this case and bringing peace to the families it has affected. There are lessons to be drawn from comparable serial killer cases which have been solved. It can only serve us well to apply such studies toward deciphering the Zodiac's riddle.
The Truth About the Green River Killer: http://www.alternet.org/story/17171/the_truth_about_the_green_river_killer
Woman Tells of Escape from BTK: http://www2.ljworld.com/news/2005/sep/20/woman_tells_escape_btk/?print