Possible solution for bomb cipher

Zodiackiller.com Message Board: Ciphers: Possible solution for bomb cipher

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Wednesday, October 01, 2003 - 08:39 pm:

Is this valid? I don't know. The code is so short and has so few repeated symbols that it's clearly open to a plethora of interpretations. Nonetheless, what follows is a solution that fits. Furthermore, it was constructed by a sequence of logical steps. You be the judge.

For ease of reference, here's the code:


My first question is the following. Why did the Zodiac feel obligated to go back and add the # character to the postscript of the Johns letter? The postscript, which reads: "The Mt. Diablo code concerns radians and # inches along the radians," means essentially the same thing with or without the #. What's the point? One possible explanation is that the Zodiac considered the # character to be a clue because the code itself contains the phrase "<some number> inches along".

The next interesting point is the ever-present Zodiac symbol (the crossed circle). As I previously suggested with the My name is... code, I believe the Zodiac may be using the symbol to refer to himself. In this case, it makes even more sense given that the symbol is positioned near the end of the code and could be a type of signature.

There are very few repeated symbols in this code. However the positioning of the symbols that are repeated is interesting. In particular, I believe the three symbols following the Zodiac "signature" may be serving as a type of key to decode the beginning of the cipher. In other words, the text may be a small, relatively easily inferable word that is unrelated to the rest of the content of the code. By identifying the word, one will identify the second letter of the code.

If the Zodiac symbol is a signature, what three-letter word could follow it? The only reasonable possibility I can come up with is out, as in signing off. If this idea is correct then the second letter of the cryptogram is T. Using this and trying to incorporate the phrase mentioned above I am able to arrive a one solution that fits reasonably well (the color coding shows equivalent symbols):

S I X + O U T

This solution has a couple of interesting characteristics. The first is that a repeated symbol is used for the letter S both times the word "SIX" occurs. This could be by design.

The next point struck me about ten minutes after I arrived at this possible solution. The result is "6 inches along 6" and the map is a Phillips 66 map. Coincidence? Perhaps. But much stranger things have been suggested...

Another possibly meaningful oddity, the John's letter postscript is basically centered on the 6 position of a large Zodiac symbol. In fact, the vertical line of the symbol crosses right between the words inches and along.

The final positive characteristic I'll point out is that the X'ed Zodiac signature has an X in the 6 position. BTW, in case you've read my Zodiac Circle Theory, it's interesting to note the 6 position is one of two X's that are not accounted for.

Now for the not-so-good news. Where is 6 along 6? Well, I went to aetv.com and looked at the really nice high-resolution pdf they have of the map. The key in the lower-left indicates 1 inch is approximately 6.4 miles; 6.4 miles is easily approximated given the key. Scaning can mess up dimensions and therefore scales. However, the map is probably close if not completely accurate. The resulting point (6 along 6 after aligning 0 with magnetic north) appears to be slightly (perhaps an inch) off the map, basically south of Cupertino. It does seem somewhat unlikely that the Zodiac would pick a place that ended up off the map. However, on the plus side, the point does seem somewhat reasonable. It is not, for example, in the middle of the San Francisco Bay. Also, BRS and LB are not shown on the map, so maybe it is reasonable...

Any thoughts or ideas?


By Tom Voigt (Tom_Voigt) (12-231-193-32.client.attbi.com - on Wednesday, October 01, 2003 - 09:14 pm:

Fantastic job Mike. Can you use Mapquest.com and post a pic of the area north of Cupertino?

By Wendi (Wendi) (dpc6682009019.direcpc.com - on Thursday, October 02, 2003 - 01:52 pm:

Wow, it would seem that all this time I've been wasting my energy bribing Tom for info when I should be bribing you!
It could be just another ploy at the six and six 340 connection, but your ideas brought up a question of redundancy; was he really meaning ALL the references to the number 6 to refer only to the 340 cipher? If so, thats a huge waste of energy to prove one point.
Your solution is the best I've seen so far.Then again, I'm usually working on this late at night after a few drinks, so my own ideas become hazy...lol.Grand effort Mike...do you ever sleep, work, or go to school?lol
I'm glad that map that was ordered is going to you.
Mapquest is almost useless, I tried.Maybe you'll have better luck.
Didn't CB operators and some military groups use "over and out" to signal the end of a conversation? Or is that just a media portrayal?
So what should I start bribing you with? :)

By Wendi (Wendi) (dpc6682009030.direcpc.com - on Thursday, October 02, 2003 - 02:18 pm:

I have several maps of the area, but either your site or my skills prevent me from posting them. Any ideas?

By ScottN (Scottn) ( on Thursday, October 02, 2003 - 04:18 pm:

Mike, why did you key the 't' in 'out' to the second letter of the cipher and not some other letter?

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Thursday, October 02, 2003 - 10:16 pm:

Wendi, Thanks.


The 't' in 'out' maps to the second letter of the cipher simply because of the symbols involved. Specifically, the triangle is the second and last symbol. If the last three characters are 'out' then the second character must be 't' (assuming this is a straight substitution code).

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Thursday, October 02, 2003 - 10:48 pm:


Thanks. I think the scale/resolution of the aetv.com map may be messed up. I did some calculation on a different map and I come out in a different location (one that's on the map though!). I want to figure this out before posting a map...


By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Thursday, October 02, 2003 - 11:02 pm:

Here's another interesting observation about the John's letter postscript. Where is the starting/stopping point of the circle in the Zodiac symbol? Mike Rodelli and others have pointed out the Zodiac almost always started the circle in approximately the 1 position (albeit this is a much-bigger-than-normal circle). Interestingly, in this case, it's in the 6 position. This could either be an explicit clue or it could be a subconscious indication of what the Zodiac was thinking about when he drew the circle.


By Alan Cabal (Alan_Cabal) (cache-mtc-af02.proxy.aol.com - on Friday, October 03, 2003 - 04:08 am:

If the NY Post was on the ball, they'd be contacting you, Mike Cole.

By Ray N (Ray_N) ( - on Friday, October 03, 2003 - 05:28 pm:

I love this sort of stuff, Mike. In fact, using intuition in combination with decryption technigues may be crucial in solving these short ciphers. In other words, since they are short, the author may have left external clues as to the message content. For example, since this message is 32 characters long, and since there is the symbol that some have interpreted as a hybrid Z/32, I wondered if this might be a clue as to the content of this cipher. What I came up with as a possible solution was:


The message fits, but when I worked out the key, there were numerous problems.

Having said that, I can find no such problems with the sub-key that would produce the plaintext you suggest. Therefore, the answer is yes this could be correct. We can definitely say that your solution cannot be disproven.

Some observations:

T is a very common consonant. There are 3 T's in your proposed plaintext but only 2 symbols representing T. Not super comfortable with this.

S is a very common consonant. There are 4 occurrences of S in your plaintext but C and O are the only symbols representing S. This is somewhat troublesome.

There are 3 occurrences of N and 3 symbols representing N. This is good.

There are 3 symbols representing I and 3 occurrences of I. Also promising.

There are two symbols each for X and U. This is not at all consistent with normal frequency distributions. Plus, this compares unfavorably with the sub-key for the first cipher in that we find no such overabundance of symbols for these letters.

In any case, I do like some aspects of it. In particular, "Zodiac Out" or "Z Out". This would be extra interesting if he had ever used this phrase when writing. Too bad there aren't more L's involved. I would suggest that even apart from the obvious shortness of the message, the odds are against this being the original message due to a couple of questionable aspects that I described above.

But my question is, what do you suggest is significant about 6 inches along number 6? Would you interpret that as 6 inches south? What is there?

Just for fun, I made a sub-key of your plaintext to compare with the sub-key for the first cipher.

Here's yours:

S=C,O T=open delta, solid square A=J,R R=I,H I=backward K,A,E X=inverted aries,L N=M,X,F C=backward F H=solid delta E=omega, lower-right filled square L=T O=G,P G=dotted circle U=D,W M=V B=backward J Z=crossed circle

Here is the Harden's key

I also wonder if I am reading your post as intended when you note that the same symbol for S is used each time in the word SIX. It appears to me the the O symbol repeats instead when it is used in place of the S in INCHES?

By Alan Cabal (Alan_Cabal) (cache-dk01.proxy.aol.com - on Friday, October 03, 2003 - 06:12 pm:

This is the good stuff. Mentzer and that recycled Maury Terry piffle is nothing. This is the motherlode.

By J Eric Freedner (J_Eric) (dialup- - on Friday, October 03, 2003 - 10:06 pm:

Yes, I agree this is interesting! In the solution I offered some time ago, I started out trying to decode RADIANS while Mike, you seem to have gone with INCHES. Would the "number six" refer to radians? I'm going to think on this one a bit more, if I may....

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Friday, October 03, 2003 - 11:02 pm:


Thanks for the kind words...


Glad to hear your ankle is going to be okay (eventually). Thanks for the thorough reply. I agree with the first idea regarding external clues. It's pretty clear to me that the Zodiac felt the cryptogram was decipherable, which is actually amazing given that it's 32 characters long and contains 29 unique symbols. The clear implication is that the Z felt there was auxiliary information that would assist in the decipherment.

The frequency distribution stats you point out are interesting, but in the end I'm not too concerned about them for a few reasons. First, as you allude to, the code is so short. It's barely longer than the alphabet itself. Laws of averages tend to break down when the sample sets get sufficiently small. Second, target frequencies are developed based on standard english usage. This assumption may not be valid if the code contains structure not found in typical english usage. For example, the Zodiac may have derived some satisfaction in the redundancy of "6 along 6". If so, this redundancy would introduce frequencies inconsistent with standard english usage. Finally, the choice of which symbols to use twice may well have been done not based on the need to supress frequencies, but based on how the Zodiac felt the cryptogram might be solved. Of course, the latter two points only come into play because the code is so short.

As for the interpretation, I propose the Zodiac meant the following. (1) Take the annotated Zodiac circle centered on Mt. Diablo and rotate it to align with magnetic north (clockwise ~17 degrees). (2) Measure 6 inches along the line that passes through the 6 position (on the Phillips 66 map itself). (3) Start looking at that point. If the Zodiac is to be believed, this should identify the location where he was planning to bury the bus bomb.

Thanks for the sub-key.

Sorry for the confusion regarding the S in SIX. What I meant was both S's are encoded with symbols that are repeated (O and C respectively). I didn't mean that they were encoded with the same symbol.


By Lapumo (Lapumo) (p50-70.as1.clm.clonmel.eircom.net - on Saturday, October 04, 2003 - 07:10 am:

One simple question Mike.....Given the scale of the map how large do you calculate the area you have pinpointed to be?

By Ray N (Ray_N) ( - on Saturday, October 04, 2003 - 01:01 pm:


I wasn't questioning the frequencies with which individual letters were used in the plaintext you suggest. As you correctly state, those would be subject to a high degree of variation depending upon the actual message particularly in light of the short length. Rather, I was referring to the number of symbols representing any one particular letter. These would be relatively unaffected by the length of the message. If, for example, there had been 4 or 5 occurrences of "S" but only two symbols used for this letter, this condition would cast serious doubt on the candidate plaintext. We don't have anything that severe here. I was only pointing out what appears to me to be the start of a trend in that general direction.

One other thing I find interesting about your solution is the concept of clues offered in "installments." In other words, the message tells us where to START, but it doesn't tell us where to go. This suggests to me that either we already have the additional information or that more short ciphers are to follow with additional instructions. Since we never got anymore ciphers, I'd have to assume we already have what we need. Also, the "Z OUT" would serve no obvious purpose other than to sign off. But we might infer that he was filling in spaces to a certain length or forcing repeats of under-used letters to facilitate decryption. Unfortunately, the letters repeated (assuming your solution is correct) only turn up new substitution symbols for them, with the exception of T, which would negate this purpose.

But assuming Z felt this was a solvable cipher, we'd have to approach it along the lines of knowing something about what the message was going to say. The codebreakers at Bletchley Park were aided tremendously by serveral crucial mistakes the Germans made with their Enigma code, not only concerning the design of the encoding mechanism but its use in the field. For example, after a short time, they learned that an extremely high percentage of messages, particularly ones coming from the upper echelon of the command structure (and therefore presumably having the most potential for inclusion of sensitive strategic information) would start with the phrase HEIL HITLER. We have 2 E's, 2 I's 2 H's, 2 L's a T and an R. In fact, this simple phrase contributed significantly to the penetration of the Enigma code.

It occurs to me that the repeat of the letters may be a signal in and of itself. C O. This could be instructions to "see circle" or the crossed circle with the X in the 6 o'clock position. Or it could be an attempt to refine the area down a bit. I tried a Google search for "circle c cupertino." There are some ranches with interesting names (Circle C, Circle Point, and amazingly Circle SIX), but I didn't look into their exact locations. If you click on the links on this page, you get a topographical map of the selected area.


By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Sunday, October 05, 2003 - 02:14 am:

J Eric,

My belief is that "nubmer 6" refers to the 6 position on the "rotated zodiac circle" (i.e. aligned with magnetic north). I further believe the use of the term "radians" only refers to the generalized notion of angular measure; in other words there is nothing special about radians and, in partuclar, nothing special about whole-number multiples of 1 radian. I describe this belief in greater detail in my Zodiac Circle theory.


I think the next post will shed some light on the subject.


Interesting stuff... I know what you're saying about "START". I actually tried pretty hard to get the code to work with the word "STOP" just because I liked the instruction better. Oh well...

I'm not quite following what you're saying about "Z OUT". I understand O and U are represented by symbols that are not repeated. But the purpose of this "key" (assuming the interpretation is correct) is only to identify the 2nd character of the code. The characters O and U are otherwise useless. I perceive the intended decoding sequence to be roughly: (1) decode OUT and identify 2nd character as T (2) Infer S as the likely first character and therefore the 26th character (3) Fit "six inches along" into position based on clue from Johns' letter postscript and O symbol in the 6th and 14th position. (4) Tweak until solved.


By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Sunday, October 05, 2003 - 02:57 am:

Here's an interesting development...

First, mega-thanks to Wendi. As you may or may not know, she has a copy of the 1969 Phillps 66 map. She was nice enough to make some requested measurements and email me multiple scans of the map.

The task was to locate the point 6 inches along vector 6 once the Zodiac symbol (circle) is aligned with magnetic north (~17 degrees E). With some basic trig, the point can be broken down into it's north/south and east/west components. Doing so, we get:

n-s = cos(17) * 6 =~ 5.74 inches
e-w = sin(17) * 6 =~ 1.75 inches

So, given a properly scaled map, we should start at the peak of Mt. Diablo as identified by the Zodiac, go south 5.74 inches, then go west 1.75 inches.

Doing this, we find 5.74 inches south is basically the very bottom of the map (almost exactly). Going 1.75 inches west puts us right at the bottom of "Stevens Creek Resevoir" (subscribers to the water theory will like this...). There is really only one road in this location. It's called "Stevens Canyon Road". Here's a current map of the area.

Stevens Creek Resevoir

So, the obvious question is: Does the location have any terrain that is consistent with "bus-bomb" terrain? In particular, the Zodiac drew a road with a hillside in the My Name Is... letter. In an attempt to answer this question, I started searching the net for pictures of the area. Below is one picture I found. The URL that it comes from is here.

Stevens Canyon Road with hillside


By Linda (Linda) (208-59-124-61.s61.tnt1.frdr.md.dialup.rcn.com - on Sunday, October 05, 2003 - 04:33 am:

Mike... You've done a great job on this. Congratulations. And thanks to Wendi, too!

By Wendi (Wendi) (dpc6682009019.direcpc.com - on Sunday, October 05, 2003 - 01:34 pm:

I was scanning pics for other people too, so you're welcome. Great job Mike!

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Sunday, October 05, 2003 - 07:57 pm:

One more thought... On the bomb diagram the Zodiac wrote "Sun light in early morning" (spelling corrected). I suspect the intent of this statement was not only to describe the operation of the bomb but also to provide a clue about it's intended geographic location. Specifically, the sun rises in the east. Therefore, the diagram implies the hillside is on the west side of the road.

I believe Stevens Canyon Rd. is consistent with this clue. From the map it appears the reservoir is on the immediate east side of the road and any hillside would have to be on the west side of the road.

Is there anyone familiar with this area that can confirm or refute this interpretation?


By J Eric Freedner (J_Eric) (dialup- - on Sunday, October 05, 2003 - 09:53 pm:

Mike, All this is strange and EXCITING! In my work on the bomb cipher, coming up with a different message, I concluded that it would be at the spillway of Don Pedro Reservoir east of Turlock. However, we both independently come up with a similar terrain, that of a lonely road beside a reservoir.

Wish I'd known of your conclusions when I was up north; I passed near Cupertino on my way back to San Juan Bautista and could have tried a side trip there to see the place and get some snapshots. More to the point: do school buses travel that route or (as I thought might be the point with Don Pedro Res.) do schools take kids on field trips to the reservoir? (Don Pedro has a big visitors' center. Yes, I actually drove out there to see for myself!)

One more question I can ask but not answer--HOW would Zodiac know about this place? He couldn't just pick it off a road map; he'd have to be familiar with the land to know when and where to plant a bomb (even if he never did). In other words, might Zodiac have once hunted in the area, does any Z suspect have ties to Cupertino, can anyone find any records of, say, a suspect having been given a traffic ticket in the vicinity which would prove he might have been there?

By Tom Voigt (Tom_Voigt) (12-231-193-32.client.attbi.com - on Monday, October 06, 2003 - 10:36 am:

Looking at the picture and the map, it seems to be a perfect location to set up such a device as Zodiac threatened. Certainly Zodiac would have been noticed if he stopped on a busy street or highway, however Stevens Canyon Road looks extremely rural and flat, with good visibility in both directions.

Not that I believe his intent was there, but if Mike is right, perhaps this was an attempt by Zodiac to be a bit more realistic with his threats.

By J Eric Freedner (J_Eric) (dialup- - on Monday, October 06, 2003 - 08:33 pm:

Is it just me, or does the map, when turned on its side, reveal the "32 squiggle" that Z favored? Look carefully and a bit artistically at Montebello Rd. around the Sunrise Winery and then on to Stevens Creek Road going...North, I think it would be.

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Tuesday, October 07, 2003 - 04:09 pm:

J Eric,

Unfortunately, my conclusions didn't exist at the time you (and I) were in Northern California. Oh well...

I'm not sure if school buses traveled on this road during the Zodiac era. I've searched in the net a little and suspect that they did, but I can't confirm it conclusively.

I have to disagree with you slightly regarding knowledge of the area. It seems quite likely to me that the geographic location of the crimes scenes were of great importance to the Zodiac. Although he may well have had prior knowledge of the general area, I don't think a detailed pre-existing knowledge was requried. In other words, if the Zodiac picked a location on a map that was, for some reason, important to him, he could have easily developed the knowledge of the area required to perpetrate his crimes.


By Howard Davis (Howard) ( - on Wednesday, October 08, 2003 - 04:18 pm:

Check with the Cupertino Historical Society and main public library for info.Also,for the bus route, contact the school Board(or other sources they can guide you to)as they should be able to give you the 1969 routes and which roads were used.
There is a large quarry off the road in question and trucks traveled that highway since the early 30's.FYI

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Wednesday, October 08, 2003 - 10:20 pm:


Thanks for the suggestions. I actually contacted the historical society and the library yesterday... The school board is a good idea.

That's interesting about the trucks; definitely problematic unless the schedule or route could be worked around.

By Linda (Linda) (208-59-124-146.s146.tnt1.frdr.md.dialup.rcn.com - on Thursday, October 09, 2003 - 03:35 am:

J. Eric asked:
In other words, might Zodiac have once hunted in the area, does any Z suspect have ties to Cupertino, can anyone find any records of, say, a suspect having been given a traffic ticket in the vicinity which would prove he might have been there?

Very interesting you have brought this up. After he had been captured in 1996, Ted Kaczynski underwent a psychological examination. In her report, Dr. Sally Johnson noted that Ted told her that the only other time he had been in trouble was when he received a ticket for "passing a stopped school bus 'approximately' 25 years ago." He plead guilty and paid a fine of $30 to the "Justice of the Peace Court." There was no indication of where Ted received this ticket; however, at the time of his evaluation (in 1996), 'approximately' 25 years ago would put you in the neighborhood of early 70's or even late 69...

Supposing that TK could be the Z (and knowing, from his own written words that he was angered and wanted revenge and didn't care who he hated), it is entirely possible that getting a ticket would have set him off in some manner, resulting in the threat by bomb against 'buses' full of school children. Of course, Z retracted his threat...which is identical to what Ted did when he threatened to blow up a plane...then retracted.

Through the Freedom of Info Act, I tried to see if there was any info on just where TK received this ticket, but was unable to come up with anything.

It would be interesting to know if in the Mt. Diablo area, there are any "Justices of the Peace Courts" that may keep old records...


By Tom Voigt (Tom_Voigt) (12-231-193-32.client.attbi.com - on Thursday, October 09, 2003 - 10:56 am:

Linda, I respect your opinions, but would it have to be a ticket issued specifically to Ted before you'd be interested? It's one thing to favor a particular suspect; I do that with Allen because of my gut feeling. However, being completely biased is a diffrent matter. Between you and Doug, 99% of your posts contain the word "Ted."

Anyway, this is one of the best threads in some months and I don't want it to turn into a discussion about the merits of particular suspects.

By Linda (Linda) (208-59-124-160.s160.tnt1.frdr.md.dialup.rcn.com - on Thursday, October 09, 2003 - 02:07 pm:

I responded this way, Tom, because the question was asked if there were any suspects who had received a traffic ticket in the vicinity...and yes, Ted is a suspect and was given a traffic ticket; and although we have no information on the exact date and/or location, Ted's note that is was approximately "25 years ago" puts this timing in and around the Z crimes and we know Ted was a Professor at Berkley and certainly could have been in the area.

I'm sorry if I offend anyone by answering with Ted's name in responses, but I thought that's what Eric was looking for...a key suspect that may have obtained a ticket. I certainly think Ted is a key suspect and his ticket for "passing a stopped school bus in and around that time" should certainly raise some interest.

Sorry, again if I shouldn't be speaking about Ted.

By Tom Voigt (Tom_Voigt) (12-231-193-32.client.attbi.com - on Thursday, October 09, 2003 - 02:41 pm:

Linda, I have no problem with you posting your opinion about Ted. However, there are several "Ted threads" already and I've noticed it's very rare for you to participate in other discussions without bringing his name into it.

Meanwhile, placing a suspect in that area is meaningless until it can be proven Zodiac was active there. Right now it's nothing but a theory in its infancy.

By Tom Voigt (Tom_Voigt) (12-231-193-32.client.attbi.com - on Thursday, October 09, 2003 - 02:44 pm:

IMHO, the Stevens Creek Reservoir area closely resembles Lake Berryessa and the similarity of Montebello Road to Berryessa's Monticello Road is also striking.

By Alan Cabal (Alan_Cabal) (cache-mtc-af02.proxy.aol.com - on Thursday, October 09, 2003 - 05:32 pm:

That area is an easy drive from the North Bay.

By J Eric Freedner (J_Eric) (dialup- - on Friday, October 10, 2003 - 12:25 am:

Linda (and anyone else not from Calif.): All "Justice Courts" were consolidated into first Municipal Courts and later Superior Courts by changes in state law several years ago. That doesn't mean all the courthouses vanished (though some may have), they just have new names. In some counties, archived files are stored in the central court in the county seat. For Mt. Diablo, Contra Costa County, county seat is Martinez. But the road in question is in Santa Clara County, San Jose is the county seat. I don't think courts routinely keep traffic violations beyond maybe 7 years, however.

By Linda (Linda) (208-59-124-160.s160.tnt1.frdr.md.dialup.rcn.com - on Friday, October 10, 2003 - 02:59 am:

Thanks for the info on the Courts, Eric. I know it's been a long time, but it might be worth a shot to do a little sleuthing. You never know what kinds of old, hand-written records may be out there, listing fines paid, etc.

Thanks again for the tips.


By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Friday, October 10, 2003 - 10:25 am:

Much thanks to Mark. He lives relatively close to Stevens Canyon Road and was nice enough to take pictures, provide commentary, and give some general insight into the area. The annotated pictures are available here.

The previously mentioned quarry is just north of Montebello and west of Stevens Canyon Road. Apparently, the trucks usually travel south to the quary and north away from the quary. Therefore, the section of Stevens Canyon north of Montebello is unlikely due to the described bombs' inability to differentiate between trucks and buses. The section south of Montebello still seems viable.

The bottom line: there is terrain in this area consistent with that described by the Zodiac.

I don't know if the Zodiac ever attempted to set up the bus bomb. I'm not even sure he intended to do it. I do believe, however, he (1) had a place picked out that was consistent with his descriptions; (2) attempted to identify that place with the Phillips 66 map, cipher, hints, etc. As of yet, nothing appears to disqualify Stevens Canyon Road from being the described location.

By Howard Davis (Howard) ( - on Friday, October 10, 2003 - 11:32 am:

It was kind of you Mark to take the pictures and explore the area and you Mike, for your work on this contraversial area of Z research.I know it is greatly appreciated.
I was concerned about the trucks setting off any kind of bomb that Zodiac depicted in his scare letter.
I don't believe Z was going to set one up and that it was another means of promulgating terror in the population using a very sensitive issue-young children-but we need to play it out anyway.
So much of the area is not conducive to the type or kind of explosive device Z lays out in his letter-but certain limited areas,as Mike points out,are possibles.
Was the overgrowth much less in certain road areas in '69 thus permitting more sunlight to be visible to make sense of Z's so-called "death machine"?
In early summer the sun would be in a different position relative to the canyons walls and any overgrowth,possibly, giving more properly angled sunlight at that time.
The photos by Mark were taken recently(?) showing the sunlight cast patterns of fall.
The truly distrubing element here is that Zodiac-laying aside the infamous 'name'-was a human being and yet,he was willing,yes even excited about frightening children and their parents,including the rest of the populace.
He must have had a very low opinion of children to do what he did and a very aberrant mind.

By J Eric Freedner (J_Eric) (dialup- - on Saturday, October 11, 2003 - 10:03 pm:

Why the warning, "you have until September to dig it up"? Trucks and maybe some buses (taking church groups to picnics in parks, for example) would travel a road during times when school was not in session.

I have an explanation, however contrived it may sound, for the bomb location I thought up in another part of the state; how about this one on Stevens Creek Road?

By ScottN (Scottn) ( on Monday, October 13, 2003 - 04:57 pm:

J Eric, it's possible that he was waiting until September to activate the bomb (although it would put him at risk to revisit the scene if someone had actually solved the cipher before then).

The bigger question I have is, assuming this fabulous work done by Mike has unlocked the 6/26/70 cipher, why Cupertino? For such a psychological killer, I think each location is specially chosen, not just for logistical purposes, but to satisfy some urging within him. Consider also that Cupertino is about 100 miles away from Vallejo. Bit of a drive to plant a bomb.

I found this interesting bit off the web:


Until the mid-1960s, Cupertino remained largely a town of ranches and estate vineyards. Then two things happened: De Anza College opened, and soon after, computers came on the scene.

Fear of annexation caused Cupertino to incorporate in 1955, and the population has since grown tenfold, to more than 52,000. Cupertino was motivated to set its original boundaries by residents who were concerned that nearby cities' attempts to incorporate the area would submerge the community's distinctive qualities and diminish home rule. In this way, "community character" has been an integral aspect of Cupertino since it was established.


Interesting that Zodiac would choose such a community.

By Howard Davis (Howard) ( - on Tuesday, October 14, 2003 - 10:38 am:

Also,it was September 27th when they voted to officially form their community.
You do have that large reservoir there and as Tom said,it bears a resemblance to the Lake Berryessa environs.
Pleasanton had a similar history and background and one Z letter had that towns postmark.All FYI

By Howard Davis (Howard) ( - on Tuesday, October 14, 2003 - 10:43 am:

Cupertino was the named after a creek or stream in the area-another water deal FYI.

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Friday, October 17, 2003 - 12:33 am:

Here's some more information courtesy of Mark. Thanks Mark.

"This time when I went out there, I went up Montebello Road, just because I had not been up it in about 15 years, while I pass through on Stevens Canyon quite a few times each year. Was surprised to find that there is a small school up in the hills on Montebello, something that I had been aware of but had completely forgotten about. When I got back home, I checked and found a website for the school, http://www.montebelloschool.org/ I had been assuming that any kids that lived up there would have been bused down to one of the schools in the valley, but that isn't the case, at least not until high school age. "

By Howard Davis (Howard) ( - on Wednesday, October 22, 2003 - 09:41 pm:

Good digging Mark/Mike.Interesting subect for sure.

By Mike_Cole (Mike_Cole) (12-224-40-230.client.attbi.com - on Saturday, October 25, 2003 - 09:16 pm:

Two more thoughts on this possible solution...

First, the letter that included the code basically consists of four parts: (1) content, (2) signature, (3) postscript (without P.S.), (4) code. Interestingly, the Zodiac signs the postscript with a small zodiac symbol. I believe this increases the probability that the zodiac symbol in the code is indeed a signature, as I proposed above.

Second, I've noticed something interesting about the misspelled word "promiced". To translate this word to a correctly-spelled word, one should replace the 'C' with an 'S'. In the proposed solution for the code, the symbol 'C' represents the letter 'S'. Now, if you want my honest opinion, I think this is just coincidence. However, one could make the case the misspelling is actually a clue...

By Tom Voigt (Tom_Voigt) (12-231-193-32.client.attbi.com - on Saturday, October 25, 2003 - 09:27 pm:

Mike wrote:
"one could make the case the misspelling is actually a clue..."

Are you listening Sean and Ray? LOL!

Mike, good ideas as always. Keep 'em coming.

By Lapumo (Lapumo) (p51-230.as1.clm.clonmel.eircom.net - on Sunday, October 26, 2003 - 07:12 am:

I think it's a fair call Mike.Perhaps the fact that he used that word in the first place is significant!