X=Z? Pros and Cons

[mike_r]

Hi-

Zodiac said he was leaving clues to his identity. Those clues do not have to be overt,
like saying "My name is." Clues to your identity can take many shapes. The Zodiac murder dates look
to be completely random until you look at them through
the filter of KQ's life. Now they seem to say. 'This is when my mother died.
This is when my father was born. This is when i first sought
attention from the public on a grand scale like I would as Z over twenty years later," etc.
You can quibble about July 4th vs. July 5th, but to do that is to ignore the other dates that match exactly. The overall pattern can't be denied--as Richard Walter and Vince Repetto apparently realize.

The power comes from essentially telling everyone who you are not only in your letters but by the dates of the murders and plenty of other things...and having nobody figure out who you are (for thirty years, anyway). The dates could not be used to identify Z. They only begin to make sense once you have ID'ed him by another means.

Mike

[Coffee Time]

It's interesting that Kjell's father passed away in November 1970 -- the beginning (or near the beginning) of the 5-month gap between the Halloween card and the Times letter. I wonder if anything of significance occurred during the 4-month gap between the Belli letter and the "name" cipher...?

[doranchak]

Hi-

KQ's mother died on December 20, 1939. His father was born on September 27, 1887. On July 5, 1947, KQ claimed he not only saw flying saucers over Auburn, CA but that he knew that they were space crafts. Nobody else at the time (only two weeks after the term "flying saucer" was created) was venturing such a guess, civilians or scientists. His story appeared on the frunt page of the SF Examiner on July 8th). Attention seeking on a grand scale. On October 11, 1958, KQ ran his first race car at the Riverside International Speedway.

Anyone see a pattern here?

You are wandering into "pure coincidence" territory here. As in, you have to definitively exclude the possibility that significant dates match due to random chance. What are the odds that KQ's personally significant dates would match 4 of Zodiac's personally significant dates? How low do those odds have to be to prove they aren't coincidence?

We can try the 5% rule. If the chances are less than 5%, then maybe the matching of dates was by design.

Let's do a quick thought experiment. How many dates do you think are personally significant to the Zodiac killer? Let's say there are 10 such dates. They would include crime dates and perhaps other notable events known only to the killer.

There are a number of dates that are personally significant to KQ. Birth dates, death dates, notable life events, and so on. How many of those dates are needed for there to be more than a 5% chance that they match at least 4 of the 10 Zodiac dates purely by chance?

(Warning: Math)

The chance that one KQ date matches one Zodiac date is: 10/365.
The chance that 4 KQ dates each match one of the Zodiac dates is: (10/365)*(10/365)*(10/365)*(10/365), or 10/365 raised to the 4th power, which is a pretty small number.
Let's say N is the number of significant KQ dates. There are (N choose 4) ways to pick 4 of them.
So we can write (N choose 4)*((10/365)^4) = p, where p represents the probability we matched 4 of KQ's dates with 4 of Zodiac's dates.

If p is at least 5% then we are not confident the dates match up by design.
Thus we want (N choose 4)*((10/365)^4) >= 0.05


That works out to about 40 dates.

Conclusion: You only need to find 40 dates significant to KQ for there to be a 5% chance that they match 4 of Zodiac's dates purely by accident. You could pick from KQ's kids' birthdays, his parent's birthdays, birth and death dates of his relatives, accomplishments in his life, etc. etc. It does not take long to find enough dates.

For comparison, let's say there are 20 significant Zodiac dates instead of 10. In this case, you'd only need to find about 20 dates significant to KQ before you can't escape the shadow of a doubt.

Now let's look at the other part of your claim, where 2 Zodiac dates fall within 5 days of a major holiday.

(Warning: Math)

A random date has a (11/365) chance of falling within 5 days of Christmas, and a (11/365) chance of falling within 5 days of Independence Day. So the random date has a 2*11/365 = 6% chance of falling within one of two major holidays.
If you pick two random dates, the chance that they BOTH fall within 5 days of 2 holidays is: 6% * 6% = 0.36%.
If we have 4 Zodiac crime dates to pick from, there are 6 different ways to pick two of them. So the chance that 2 of the 4 crime dates fall within 2 holidays is: 6 * 0.36% = 2.16%.
But we haven't considered other major holidays. What if we included Halloween and Thanksgiving?
After doing the math, the chance that two of four Zodiac crime dates both fall within one of four possible holidays is: 6*((44/365)^2) = 8.7%


8.77% is high enough for this to be purely coincidental. It gets worse if you include more crime dates.

So again, we have not escaped the shadow of a doubt.

Also, someone please check my math for mistakes!

[mike_r]

Hi-

But let's look at it this way: There were only four Zodiac murder dates. KQ only had two parents and one date matches each. (There were only three "parent dates" in 1968-9, since KQ's father was still alive.) We won't even get into the possible Freudian significance of killing on dates related to your parents. He behaved like Z for the first time only once in 1947. He ran his first car at Riverside, which just happened to tie into the Z case, only once. There is an interesting date related to his birthday but I won't get into that right now. And there are other dates, like June 26th and November 20th, that relate to a letter and an interesting article related to the Z case.

And let me say this about July 4-5. Let's say that you found a suspect who was born on the 4th of July and married on December 25th. If you dared to say that he matches Z dates because Z said something about Christmas and the 4th of July, people here would shout you down as being full of BS because Z actually killed on December 20th and July 5th. So you can't win. I stand by the fact that whatever he said about July 4th, Z waited until July 5th to pull the trigger and that date matches KQ's UFO sighting. December 20th is an exact match.

And this is not my only evidence. KQ is also the only suspect I've ever heard of who ever touched a piece of Monarch sized paper. He also lived two blocks from one of the crime scenes (ALA didn't live that close to any of the Vallejo crime scenes; the IHOP was not a crime scene). He was the only person ever to be named as a suspect who was spoken to by the police near a Zodiac crime scene after one of the murders.

That is still only a fraction of my evidence. There is even more date related evidence.

Mike

[Norse]

Part of the problem here is that we cannot possibly know in what way these dates would have been significant to a possible killer. They're very different on the face of it. Birthday of a parent is completely different from the date of a bizarre event in the life of KQ.

To put it flippantly: Was the BRS attack a "commemoration" of the UFO business? That seems incredible to me. To kill on the birthday of a parent makes sense - that is, it makes sense that this combination (birthday of parent + murder) would carry some meaning to a crazy killer. The other combination does not make sense in the same way. Was the UFO business the birth of Z in some sense, the emergence of KQ as a pathological attention seeker? Was it this "genesis" he paid some sort of homage to many years later when he attacked DF and MM? It seems like a stretch to me - and it would need further explanation to be readily acceptable.

Just my take on it.

[Norse]

Also, someone please check my math for mistakes!

It's completely off! Never seen such shoddy work in my life!

On a serious note, the holiday point is an interesting one (as is your post as such!) I would add - to the pure percentages, so to speak - that it's a bit dangerous to operate with "close to" when looking for patterns. Why would a killer choose to strike on a holiday? Well, there could be many reasons for that - but the bare fact of it makes some sense in itself. It's a holiday, a significant stand-out date in itself. To do something significant on a significant date makes sense. To do something on a date close to (a couple of days? five? ten? where does one draw the line?) a significant one is a very different matter. It requires a different kind of explanation. *

* This as a general remark - it doesn't pertain to KQ per se. In fact, the holiday angle seems superfluous enough in KQ's case, since the dates in question would have been significant to him anyway, regardless of holidays.

[snooter]

no grand jury indictmnent with evidence of this nature..its just not goin to happen ..that being said this dates of importance is interesting and my take is it is worthy of a good look see..but the maths wizard here laid it all to waste..that is nothing to get too worked up over..all our present POI's suffer near the top in need of "beyond a shadow of a doubt"..heck my gut is X and TK are worthy POI's and do deserve scrutiny..mike has done a hell of a job on this..guess my question is what the hell are we missing with X that is right our in the open but we fail to see it..i dunno may be an employee know something but his brakes failed one day and he went off the cliff

[doranchak]

But let's look at it this way: There were only four Zodiac murder dates.

How do we know that for certain?

KQ only had two parents and one date matches each. (There were only three "parent dates" in 1968-9, since KQ's father was still alive.) We won't even get into the possible Freudian significance of killing on dates related to your parents.

This is an artificial significance if you can't show the dates aren't simply coincidental.

And there are other dates, like June 26th and November 20th, that relate to a letter and an interesting article related to the Z case.

So, even if we presume only 4 murder dates, the list of Z correspondence dates is quite extensive, greatly improving the chance of matching random events in KQ's life.

And let me say this about July 4-5. Let's say that you found a suspect who was born on the 4th of July and married on December 25th. If you dared to say that he matches Z dates because Z said something about Christmas and the 4th of July, people here would shout you down as being full of BS because Z actually killed on December 20th and July 5th. So you can't win. I stand by the fact that whatever he said about July 4th, Z waited until July 5th to pull the trigger and that date matches KQ's UFO sighting. December 20th is an exact match.

It's not enough to "dare to say" there is a pattern to the dates. You have to demonstrate that it isn't just happening by chance, either by showing how difficult it would be for the dates to match in the first place, or by showing some other direct evidence that it was designed by the suspect. Otherwise, there are multiple plausible explanations.

That is still only a fraction of my evidence. There is even more date related evidence.

I'd be interested in hearing more about that. Date-related patterns have come up before (example). They are fun to explore but I'm not yet aware of any discoveries that escape the shadow of coincidence, except perhaps for the crimes occurring primarily on weekends.

My curiosity can't resist figuring out the odds of random dates falling on weekends, so here goes. Let's say Fri, Sat and Sun are included in our "weekend" definition, and there are 52 of each in any given year. So the chance of one random date falling on a weekend is (52+52+52)/365 = 43%. If we say that Zodiac has exactly 4 murder dates, then the odds that all 4 happen fall on a weekend by chance are: 43% * 43% * 43% * 43% = About 3%.

[masootz]

z operated during the weekend. any significance of dates beyond that takes second fiddle to the fact that z operated during the weekend.

[Norse]

Yeah - and that in itself, i.e. that he operated on weekends, makes sense. It fits the bill, so to speak. In establishing a pattern it's important that said pattern seems intuitively...right. Which the weekend thing does, to the point where one can say that the alternative, viz. that these dates are all random (he could just as well have struck on a Tuesday, two Wednesdays and a Thursday) seems less likely.

If I, for instance, theorize that Z was a 9-4 guy who didn't have time to cruise for victoms during the week, then this seems to have some merit based on the facts.