I had forgotten about the "cipher letter writer" wording and I agree that it was copied.

My guess is then that Harden was perhaps concerned about the worksheets presentation to Lynch and wanted to add a code key. And wanted to do so anonymously as not to appear pushy. Whatever the reason was consider the following points:

1) Unredacted "Not involved, letter from anony. (school teacher) cracking cryptogram" in the FBI files: http://www.zodiackillersite.com/viewtop … =75&t=4088
2) Handwriting similarities: http://www.zodiackillersite.com/viewtop … =10#p75884
3) "Criptograms and word puzzles is one of my pleasures" correlates strongly with Harden.

As discussed previously, it is possible that the letter was mailed before the outing. Try to imagine the state of mind the Hardens were in after pulling some all nighters and actually solving the killer’s code, presumably being the first ones to do it. They must have been in doubt on how to handle it.

If that is so, Donald didn’t express that doubt in his subsequent interviews.

August 9: SF Chronicle publishes report about "cipher letter writer" code cracked by Harden
August 10: "Concerned citizen" key postmarked
August 11: Key received by Vallejo Police Department
August 12: Vallejo Times-Herald publishes article, "Is ‘Robert Emmet’ in Cipher?’. Article claims Hardens are hiding:

August ??: Vallejo Times-Herald quotes Harden’s denial that they are hiding:

It references the Tuesday article so that quote was definitely after August 12.
Donald gave a substantial interview in that article, here it is in full:

https://www.evernote.com/l/AAEQmtwSJ39I … jsSfJch19Q

So, maybe he didn’t send the code key anonymously. Or, after suddenly wanting to become anonymous after not being anonymous, he decided not to be anonymous. I think it makes more sense that he didn’t send the code key. Which leaves the FBI indication of "school teacher" as a mystery.

I had forgotten about the "cipher letter writer" wording and I agree that it was copied.

My guess is then that Harden was perhaps concerned about the worksheets presentation to Lynch and wanted to add a code key. And wanted to do so anonymously as not to appear pushy. Whatever the reason was consider the following points:

1) Unredacted "Not involved, letter from anony. (school teacher) cracking cryptogram" in the FBI files: http://www.zodiackillersite.com/viewtop … =75&t=4088
2) Handwriting similarities: http://www.zodiackillersite.com/viewtop … =10#p75884
3) "Criptograms and word puzzles is one of my pleasures" correlates strongly with Harden.

The Concerned Citizen card stated "Dear Sergeant Lynch. I hope the enclosed "key" will prove to be beneficial to you in connection with the cipher letter writer. Working puzzles criptograms and word puzzles is one of my pleasures. Please forgive the absence of my signature or name as I do not wish to have my name in the papers and it could be mentiond by a slip of the tongue. With best wishes. concerned citizen".

Not only was Harden’s name already publicized, making the "absence of my signature or name" a pointless statement, it is extremely unlikely a degree educated school teacher would type a communication with incorrect punctuation and misspell "cryptogram". This communication was either a random helpful citizen (or possibly somebody else). But a person who likes puzzles and solving a fairly complex cryptogram by providing a key, while simultaneously misspelling the word, seems unusual.

Here is a newspaper extract from the August 4th 1969 Vallejo Times-Herald, stating "Police received a few anxious telephone calls from concerned citizens Sunday, but no leads to the identity of the cipher writer who claims he killed two teenagers on Lake Herman Road and a young woman at Blue Rock Springs. The callers wanted to know if police had caught the man who confessed the slayings in letters to Gibson Publications and two San Francisco newspapers. His three cryptograms, sent with the letters and supposedly giving clues to his identity, still were in the hands of a Navy Cryptographer who at last report had not solved them". Was this newspaper article the origin of the "concerned citizen" offering his help to Sergeant John Lynch on August 10th 1969?

Not only was Harden’s name already publicized, making the "absence of my signature or name" a pointless statement, it is extremely unlikely a degree educated school teacher would type a communication with incorrect punctuation and misspell "cryptogram". This communication was either a random helpful citizen (or possibly somebody else). But a person who likes puzzles and solving a fairly complex cryptogram by providing a key, while simultaneously misspelling the word, seems unusual.

Found the following 2 pages in the FBI files, on both pages cryptogram, crypto and cryptic is spelled as cript.

That is true Jarive, but the fact that the typist in those documents cannot spell cryptogram, isn’t evidence that Donald Harden, an educated school teacher, wasn’t able to either. That would be like saying I cannot spell "environment" correctly, is somehow evidence you cannot either. I assume that the Harden’s were interested enough in puzzles and cryptograms to tackle the 408 and know how to spell it, whereas the typist in the above documents we know nothing about. Only that they spelled "breaking" and "ciphers" incorrectly as well.

it is extremely unlikely a degree educated school teacher would type a communication with incorrect punctuation and misspell "cryptogram".

it is extremely unlikely a degree educated school teacher would type a communication with incorrect punctuation and misspell "cryptogram"…….and be the Zodiac Killer!

This is exactly why the Harden’s were never suspected. Donald was a married teacher with a daughter, who also helped, to solve a murder case! The Hardens loved Newspaper correspondence with dozens of ‘To the Editors’ recorded by them (not including the numerous submissions with fake I.D Like Zoe.D.Ack). Below is the real reason why Harden sent the Concerned Citizen letter with the misspelled "cr1ptogram" …What else could piss off a teacher more than poor spelling from his own local paper "CYRPTOGRAPHER’ & "CYROPOGRAM" (Teacher – Kiddies, school bus, Pencil Light, Busy work)

And further more, once you accept that the Harden’s sent the ‘Concerned Citizen’ card (as per FBI notes) you have to take in the consideration of Harden’s work sheet stating ‘Signature’ on the 6th line of his work sheets!

This was once again a really great episode! Clearly explained and very comprehensive. Thanks a lot for this great work! I hope so much that we will be able to crack z340 some day.
I’ve had a lot of things going on lately and I’ve been fishing a lot as compensation. I’ve barely spent any time with z340. But such videos motivate me again!

What is your personal opinion Dave for the 18 unsolved characters? Which answer resonates most with you?

This was once again a really great episode! Clearly explained and very comprehensive. Thanks a lot for this great work! I hope so much that we will be able to crack z340 some day.
I’ve had a lot of things going on lately and I’ve been fishing a lot as compensation. I’ve barely spent any time with z340. But such videos motivate me again!

Thanks Largo! I look forward to your continuing efforts.

What is your personal opinion Dave for the 18 unsolved characters? Which answer resonates most with you?

"Filler" is the one I lean to the most. Especially since "qEHM" seems to be copied directly from above. But I’m open to other ideas since it’s not a 100% slam dunk "we know it for sure" explanation.

This was once again a really great episode! Clearly explained and very comprehensive. Thanks a lot for this great work! I hope so much that we will be able to crack z340 some day.
I’ve had a lot of things going on lately and I’ve been fishing a lot as compensation. I’ve barely spent any time with z340. But such videos motivate me again!

Thanks Largo! I look forward to your continuing efforts.

What is your personal opinion Dave for the 18 unsolved characters? Which answer resonates most with you?

"Filler" is the one I lean to the most. Especially since "qEHM" seems to be copied directly from above. But I’m open to other ideas since it’s not a 100% slam dunk "we know it for sure" explanation.

Dave,
Is there any way to examine the 408 and determine if a message was attempted but failed due to creator error? In other words, can we know that Zodiac TRIED to code a message, but screwed up enough to make it nearly impossible to solve?

Dave,
Is there any way to examine the 408 and determine if a message was attempted but failed due to creator error? In other words, can we know that Zodiac TRIED to code a message, but screwed up enough to make it nearly impossible to solve?

I think that can be very tricky, since it’s usually only possible to verify a coding error by figuring out what the intended message and crypto system were in the first place.
A good example is a cipher created by BTK which couldn’t be solved until he gave details about it after his capture.
https://www.tandfonline.com/doi/abs/10. … ode=ucry20
Turns out he made mistakes when creating a bifid cipher that initially prevented the FBI from decrypting his message.
But I’m not sure at what point during that impediment one could say the cipher definitely had mistakes during its construction, since any lack of solving can be attributed to the lack of a key, or the lack of knowledge about exactly what kind of cipher is being used.

I fully endorse Dave’s suggestion of a missing line. Whether you subscribe to this model or not, it’s clear he missed a word out in the encoding process (likely people). So, he either intended to leave 12 characters or 1 character left after his known message. The search for a decipherment of the 18 characters is likely a wild goose chase, because it was never intended. Upon realization of his mistake on completion, he simply used filler in frustration to his obvious error.