Hey guys,

I am going to be talking to a woman who works at the Smithsonian Institute’s National Postal Museum on the phone this week. Please let me know if you have any specific questions that I should ask her. Thank you.

Thanks, what questions are you planning to ask?

I was going to ask her about Sunday PM postmarks, Mare Island, and hand vs. machine cancelling.

I’d like some specific questions from you guys.

I conversed with a so-called Rincon Annex and San Francisco USPS expert. I got zippo out of him. I also tried the USPS Historian’s office — more zippo!

So that aside, is the conclusion the following?:

The postmark codes represent machines and dies, not neighborhoods where letters were mailed.

The Zodiac letters postmarked ‘San Francisco’ were either mailed in San Francisco, in San Mateo County or in part of Santa Clara county.

Letters mailed from Mare Island were typically not postmarked ‘San Francisco’.

I conversed with a so-called Rincon Annex and San Francisco USPS expert. I got zippo out of him. I also tried the USPS Historian’s office — more zippo!

So that aside, is the conclusion the following?:

The postmark codes represent machines and dies, not neighborhoods where letters were mailed.

The Zodiac letters postmarked ‘San Francisco’ were either mailed in San Francisco, in San Mateo County or in part of Santa Clara county.

Letters mailed from Mare Island were typically not postmarked ‘San Francisco’.

Great work! I was unable to speak with anyone unfortunately.

As to your post, yes, I think those are pretty accurate conclusions.

It seems disappointing, but on the other hand, we have dispelled a long-held belief about what these codes meant – something even the yellow book perpetuated. Sometimes, things like this can be as important as discovering something.

Chaucer I agree. And I’m still wondering if Law Enforcement understood the postal codes, or indeed may have thought they represented neighborhoods. I’ve never seen any indication that LE considered the possibility that the Zodiac mailed the letters from and/or resided in the South Bay, which is entirely possible.

Just a brief remark with regard to the shirt pieces: The idea that he went to extra lengths to make sure the missives containing shirt pieces were not, so to speak, lost in the mail is certainly interesting – but I’m not sure I buy it 100%. He did send the first piece “normally”, after all – and I don’t think he was worried about running out of pieces: he had a larger piece from which he cut out smaller pieces, suitable for enclosing with letters. He very likely also sat on other items which could – should he need it – be used to prove the authenticity of his communications.

But that’s a minor point. This is very good work – thanks to everyone who has contributed. The difference between these three letters and the rest is noteworthy in itself. And if it can be demonstrated that said difference is the result of something Zodiac did, actively (like dropping them off at the Rincon Annex) – well, that’s extremely interesting.

Well done, everyone – I’m impressed.

Just musing a bit here, so bear with me: Zodiac normally mailed his letters, well, anywhere within a relatively large area (all mail collected in said area was sent to a distribution center, sorted and then re-distributed to various zones/zip codes/whatever). My hunch is that he didn’t do this at the nearest mail box from his house, or place of work – but that he’d rather drive off somewhere to make the delivery, perhaps opting for different locations (if he was worried at all about this aspect). Anyway, the majority of his letters were mailed somewhere within “San Francisco” (not the city but the larger area we’re talking about here), dropped in regular mail boxes, and canceled by machine at a distribution center.

But a small handful of his letters were not canceled by machine – they appear to be manually canceled. And the theory proposed above is that the reason for this is that Zodiac cut out the middle man for these letters – and delivered them directly to the hub/center (Rincon). Right so far?

Well, let’s say that this has merit (I think it’s an intriguing theory myself – but it must be established that what we’re looking at isn’t coincidental, i.e. that the manual cancelling can’t be explained in any other way): disregarding his motives (his exact reason for deviating from the routine), can we reasonably speculate that what he did suggests someone who had more knowledge about how mail was distributed than the average person?

<But a small handful of his letters were not canceled by machine – they appear to be manually canceled. And the theory proposed above is that the reason for this is that Zodiac cut out the middle man for these letters – and delivered them directly to the hub/center (Rincon). Right so far?>

<Well, let’s say that this has merit (I think it’s an intriguing theory myself – but it must be established that what we’re looking at isn’t coincidental, i.e. that the manual cancelling can’t be explained in any other way): disregarding his motives (his exact reason for deviating from the routine), can we reasonably speculate that what he did suggests someone who had more knowledge about how mail was distributed than the average person?>

Norse I believe we explored that theory but I don’t think we established anything. It’s more likely the three hand-postmarked letters went into the normal system but for whatever reason received hand stamps. An automatic machine could have had a maintenance issue, and/or the letters were rejected for some reason — one reason might be that the inclusion of a shirt piece or other item could have made the envelope(s) too thick or unshapely for the automatic machines to handle.

I think it’s important to note that the postal system and how to mail things were some things that most Americans were pretty knowledgeable about in the 1960’s and 70’s. Unlike today, it was the primary form of communication behind telephones, and people used it all the time. It’s probable that Zodiac was as adept at using the mail as most other Americans at the time.

Great job all! Just a thought and do you guys know where the Letter Zodiac sent the same day after the article challenging him ? He had to live or work close by to get back to them that quick on the same day in my opinion. Could be telling and thanks.

Also believe that letter was written on the Woolworth paper that could have only been bought in one of the two SF stores in the area. Unless Zodiac already had that on hand from a purchase before. He most likely went out and bought the paper , wrote his note and mailed it back all in the same day. Location where he mailed this from again can be very telling in general where he either lived or work.

Sorry, which letter was that? What date?

Sorry, which letter was that? What date?

Not nearly sure but maybe the August 4th 1969 letter. Yea think this is the one and only one written on paper from Woolworth’s.

Again he had to read the paper that day with LE question him if he was really the killer. Most likely then bought the paper in a hurry and the only one ever written on the Woolworth’s paper. Then back somewhere to write his letter and have it sent to respond in the same day. On the letter it’s post marked in SF but asking if you guys know where it was sent in the area of SF ? Again great job and think this could be telling. He seemed not to busy in SF that day to get that all done.

It’s my understanding that ALL letters were written on Woolworths paper but the August letter was specifically Eaton.

Correction if I am wrong please

Soze