One of the most unusual things about this case is that the Zodiac stopped killing long before he vanished. So when people ask "why did he stop killing?", they need to remember that he kept writing, in fact his writing intensified.
Some have suggested he changed and that he came to enjoy letter writing more than killing. I think this is very naive thinking, naive because it fails to acknowledge the type of killer Zodiac was, and the extreme nature of killing. He killed up close with a knife. He claimed it was fun, and he compared it to sex. The idea that he would find letter writing even more enjoyable seems unlikely.
There’s also the suddenness and the timing. It’s not accurate to say that he slowly evolved from killing to writing, in fact he switch suddenly at the point where his killings had reached their greatest frequency. If he had come to prefer letter writing surely the change would have been a slow shift from one to the other, killings decreasing as letters increased. But his killing hits an invisible wall. And from that wall his writings suddenly spike. This isn’t a slow evolution, this is a forced change.
I think there is a more plausible explanation. When investigators noticed that the Zodiac only killed on weekends they concluded that the best explanation was that his circumstances, or schedule was such that he could not find time to kill during the working week. There are other explanations, but this one is rightly regarded as the most likely.
In a similar line of reasoning, I think the most likely explanation for the Zodiac’s ceasing to murder is that his circumstance changed in such a way that he was no longer able to murder, but was still able to write. The writing became a substitute for an activity he was unable to engage in, and this is reflected in the way the writing changes after Stine. His next letter is about a bomb, it’s the perfect way to achieve results without actually killing. It’s clear that letter writing has become a surrogate for killing. But make no mistake, someone who has groaned with delight as they stab someone isn’t going to suddenly find letter writing so superior that they would spontaneously switch.
People who believe this willful change theory put too much stock in free will. We are creatures of habit and behaviour. It’s not just that serial killers rarely change, it’s that people rarely change.
But what if we added fear into the mix? Suppose the letter writing was almost as much fun and had the added benefit of being far safer. Would that extra benefit entice the killer to switch? The Zodiac took huge risks, he killed in daylight, he killed in built up area’s, he wrote his longest letters after Stine. He wasn’t that scared.
Why would he stop hunting? An activity he so enjoyed? Just to write about it instead? Why do people retire, because they want to, or because they have to?
There are lots of other plausible theories, but I am arguing that in the absence of other evidence the best and most likely remains that something happened that made it so that he was unable to kill and only able to write.
Individuals environments and personal situations change, the individual merely "adapts" whilst being held to the whims of his or her innate biology.
To answer, The individuals personal circumstances improved there by alleviating the affects of biological whims, or maybe he sought medical trearment?
Many see Stines Murder as proof that Zodiac was a dull minded criminal whilst neglecting the simple fact he probably wanted to get caught in a quasi suicide attempt…
The Answer will probably never be known.
Yes, dyslexia is probably my first undiagnosed language.
I like the quasi suicidal angle.
However it’s just not consistent with the behaviour of serial killers. You can’t just wave that away by saying, "oh but he was different", "or what about BTK?", well what about the thousands of apprehended killers the overwhelming majority of which don’t stop.
He explicitly states in a letter that he enjoys killing people and equates it with sex. That surely put’s the likelihood of him quitting cold turkey somewhere near the likelihood of a sexually active person becoming a spontaneous celibate. We can’t rule it out, but it surely seems very unlikely. It also doesn’t mesh with the known timeline, the frequency is ramping up, the savagery is ramping up, the thrill is ramping up and then boom he stops.
And we have people actually saying he stopped because he couldn’t top the thrill? That’s not how the brains reward systems works. This behaviour would have caused a huge chemical release that from what we know from thousands of other killers is quite addictive. "well that’s the best cocaine I’ve ever had, probably never going to get any better, I suppose I’ll stop while I’m ahead." Saying he stopped because Stine was the ultimate thrill sounds good if from a poetic narrative view point, we may intuitively feel that’s how we work, but science says it ain’t true, we’re are insatiable creatures.
And letter writing as a substitute for killing? Be reasonable, if we were to scan someones brain whilst they stabbed someone and compare it to a brain scan of them writing about stabbing someone, sure it would be similar, but there would be huge differences in the intensity. That intensity would be mind blowing, you don’t just walk away from that kind of stimulation.
I think he was somehow restricted from being able to go out and kill on weekends and I don’t think he would have given it up so lightly. I still contend it’s the most likely explanation based on all available evidence.
What Zodiac wanted was attention and as much power as possible. To get that max attention, he needed to do something striking. Writing letters saying "Hey, I’m evil and I’m smart, you have no idea!" out of nowhere wouldn’t have worked, obviously. But once he got that attention, maybe "the game" was not funny for him anymore. Or mayben=, yes, something in his life changed and had him stop the killing. Remember BTK? He was as elusive as can be, LE considered him an evil genius while he was just the average Joe, and he had several long breaks in his "career" as a killer because… he started a family! So anything is possible. Maybe Zodiac started getting a lot of attention in a different, legal and healthy way, so he just stopped murdering people and writing letters to newspapers about it.
I think these idea’s are intuitive. They reflect our natural way of looking at the world. We might think about power struggles and history and life experience and base our understanding of Zodiac’s motives on that.
I think we can do a lot better. Thousands of serial killer have been apprehended and studied. We also have available a much deeper understanding of even normal human behavior.
We know what happens inside the brain when people murder. It’s enormously stimulating, so stimulating it can burn neural receptors. This burn is what causes desensitisation, it’s probably the reason killers often take a brief pause between killings, it’s also the reason they often seek bigger thrills. We see this in all types of highly stimulating behaviour. All stimulating behaviour appears to be addictive, but for some reason we often don’t become addicted to normal behaviour, the best explanation for this is that we have developed other mechanisms to keep those things in check. But when people engage in stimulating behaviour outside the norm, they often experience feelings of addiction.
When profiler’s suggest that Zodiac is a thrill killer, and get’s a thrill similar to sex from his crimes, they do so for good reason. It’s what years of serial killer data tells them. Zodiac himself tells us what it’s like. He can relive these feelings through letters, but that’s just not the same.
It’s such a gross underestimation of the powerful effect killing has on the mind.
Killers are killers for neurological reasons, their brains are simply made in a certain way that prevent them from having benevolent feelings for other human beings, a way that actually pushes them to hurt others for their own satisfaction. I think this is different from addiction. I also think Zodiac was different because he killed to undirectly impose his will to an entire community. He fed on power. Knowing that he was on the mind of so many people, that they feared him, here was his thrill. To me, he used murdering people as a tool for notoriety. He didn’t kill to kill, he killed to achieve omnipotence. And he wrote letters about killing because he knew it would shock society at large and make him a ubiquitous threat.
That’s right, psychopathy is the most common reason people don’t have inhibition’s towards killing. But it merely removes the road block.
Not all psychopaths kill, in fact most don’t. So why do some? In the vast majority of cases it’s related to stimulus, usually sexual, pain, thrill and pleasure. You can generally determine if this is the case based on the way the crimes are committed. Up close kills offer the greatest stimulus. You don’t have to go far to find accounts of the thrill of killing and it’s well documented with serial killers. This thrill whether sexual or not is extremely powerful, it’s a chemical explosion. Most killers do report becoming addicted to it. The Zodiac indicates that he get’s an enormous thrill from killing, he’s likely being truthful. His killings were up close and brutal.
Power is often part of the thrill, but again the power of letter writing compared to the power felt when killing, there is no comparison.
Sure, but I really believe he needed to feel that power over the Bay inhabitants, and his letters were somehow the continuation of his attacks. Killing meant overpowering his victims, writing tauting letters meant overpowering the whole Bay area.
With the matter of the Zodiac i see the murders and power trip as a means to alleviate negative feelings in the individual, a anti-depressant of sorts. I think he implicitly suggests this in his writings and actions.
What causes a psychopath to initially and repeatedly kill? That depends on every case, nothing is clear cut in psychiatry.
Yes, dyslexia is probably my first undiagnosed language.
I agree. But when it comes to the extreme’s psychology starts to become more constant, it’s in the softer cases we see variation, the more extreme pathological behaviour often is predictable. It’s speculative, but I think he may well have killed to alleviate some kind of anhedonia, but if that’s the case all the less reason to cease. And the need clearly remained or the letters would have stopped too. The idea that it lessened enough for him to find writing sufficient, doubtful, by this point killing would have been as easy for him as writing, so other than risk there is little reason to choose the vastly lesser experience.
It’s sounds like a good narrative, almost poetic to imagine a killer, now sated returning to normal life, it’s positively Byronic. I think it captures the imagination. Plus people just love examples that deviate from the norm, it makes the Zodiac seem more unique. But this does not make it particularly likely. In the absence of evidence we should go with the most likely explanation. The most likely explanation is that he was no longer able to kill, or killing became very difficult. I’m not saying what that thing was, maybe it was a big environmental change, but it would need to be a big one.
Or maybe he kept killing but simply did not send letters to boast about his crimes, like he said he would.
Well said.
Do bare in mind that it isn’t known if he ever actually stopped killing after Paul Stine. There certainly is however a sizeable hiatus between Stines murder and any murders the Zodiac is a suspect of (to my knowledge). With that said the time between Zodiacs attacks was shortening after each and up until Paul Stine.
So where does that leave us? what brought him to such a sudden stop?
I suggest the most plausible is that the Zodiac overdosed on exhilaration the night he killed Stine. To say it bluntly he Shit his pants and didn’t resurface as a murder for many years or if ever.
Will power certainly exists, The Zodiac needed a shock to quit his habit and it’s not foolish to think that he straightened up in life after such a reality check.
Yes, dyslexia is probably my first undiagnosed language.
Zodiac probably never stopped killing just, as he claimed in his Nov 9th 1969 letter, stopped writing/bragging about his killings:
Zodiac letter November 9th 1969
sent to the San Francisco Chronicle
Quote:
"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 police shall never catch me, because I have been too clever for them."
Hi, english is not my first language so please bear with me 
Zodiac probably never stopped killing just, as he claimed in his Nov 9th 1969 letter, stopped writing/bragging about his killings:
Zodiac letter November 9th 1969
sent to the San Francisco ChronicleQuote:
"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 police shall never catch me, because I have been too clever for them."
Yeah but he lied about a lot of things, What is factual however is the hiatus of possible Z crimes after stines murder. The thread asks why even in light of the above letter.
Yes, dyslexia is probably my first undiagnosed language.
Quote:
"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 police shall never catch me, because I have been too clever for them."
Sounds like a kid trying to quit an argument he knows he cannot win ^^
