I know that Mare Island was the home of the Naval Shipyard and many people in the surrounding area were employed there, but did people live on the Island itself during the 1960’s and 1970’s? Were there civilian homes and neighborhoods? Or was it completely owned and occupied by the U.S. Navy?

Barracks for enlisted men and homes for the brass.

Thanks, Tom.

That’s what I thought. Bearing in mind that enlisted men didn’t really work 9 to 5, Monday to Friday job shifts (and Zodiac implies that he does), we can PERHAPS exclude Mare Island from Kim Rossmo’s geo profile. One of the other three hot spots of Rossmo’s was an area just to the south of an area called Port Costa. This area is entirely uninhabited park land. So we can PERHAPS exclude that as well.

That leaves American Canyon/Napa Junction as the only inhabited hot spot of Rossmo’s three.

Another thing to consider is that Zodiac referred to his "good times DOWN IN VALLEJO". This suggests PERHAPS that he lived north of Vallejo since people often refer to areas south of them as "down" ("down south").

Now, I know there is A LOT of supposition here. We are assuming Rossmo’s geo profiling is accurate and sound. We are assuming that Zodiac did not live anywhere else besides these hot spots. We are assuming Zodiac was not military and did not live on Mare Island.

Still, if we believe that Rossmo’s study is accurate and sound, then we can perhaps we can narrow down the possible locations of Zodiac’s home even further.

I’m not claiming any major breakthrough here. Just more food for thought. I’m happy to here reasoned disagreement with my ideas.

"good times DOWN IN VALLEJO". This he didn’t write.

"In answer to your asking for more details about the good times I have had in Vallejo".

I did a search for Combat Systems Technical School Command on this site and nothing came up. People were trained here in cryptology. It is (was?) a facility at Mare Island. I’m not sure how long it has been around, but it goes back to at least 1961 from what I have gathered so far. Is anyone familiar with this?

One thing I like to do is to search bay area obituaries. I’ll type in something like "San Francisco merchant marines obituary." This time I searched for "Vallejo, CA cryptology obituary" and I found an obit of a woman, and part of her obit says "In 1985 she was sent to KY57/KY58 Cryptography School at Combat Systems Technical School Command in Vallejo, Ca."

So I have been looking into Combat Systems Technical School Command and found that it is (was?) part of Mare Island. I have not heard about this before, so I am doing some further research and was wondering if anyone had any input.

Good searching technique ophion1031.
In regards to the ‘KY’, these were a series of cryptographic devices (hardware), e.g.;
https://en.wikipedia.org/wiki/KY-57
I very much doubt that ‘KY57/KY58 Cryptography School’ taught what we would consider
as cryptography – different methodologies for enciphering information.
Rather, that School would have taught one of two different job activities;
The procedures to load the cryptographic key into the device and set the device for
operation (when it would have been attached to a communications system), or
The maintenance and servicing knowledge necessary to repair the device, if the device
was returned to a base level technical depot.

The analogy is comparable to someone who is taught how to set up the possible sewing
patterns on an electronic sewing machine and operate it, or
To perform maintenance and repair of an electronic sewing machine by being taught
to identify which circuit boards/relays/switches have failed and need replacing.

So to be clear, I understand that ‘KY57/KY58 Cryptography School’ is either for teaching
how to set and operate the device (Operator Technician), or how to maintain and repair
the device (Repair Technician) – NOT how to design or reverse engineer whichever
cryptographic method(s) different devices can use to encipher information.

You would probably have to seek the advice of someone who was trained as a U.S. Army
or Marine Corp radio operator, preferably from the late 1980’s onwards, so you can be
comfortable that what I am asserting is correct.
Cheers

"good times DOWN IN VALLEJO". This he didn’t write.

"In answer to your asking for more details about the good times I have had in Vallejo".

You’re absolutely right. That’s what I get for posting on 2 hours sleep.

Good searching technique ophion1031.
In regards to the ‘KY’, these were a series of cryptographic devices (hardware), e.g.;
https://en.wikipedia.org/wiki/KY-57
I very much doubt that ‘KY57/KY58 Cryptography School’ taught what we would consider
as cryptography – different methodologies for enciphering information.
Rather, that School would have taught one of two different job activities;
The procedures to load the cryptographic key into the device and set the device for
operation (when it would have been attached to a communications system), or
The maintenance and servicing knowledge necessary to repair the device, if the device
was returned to a base level technical depot.

The analogy is comparable to someone who is taught how to set up the possible sewing
patterns on an electronic sewing machine and operate it, or
To perform maintenance and repair of an electronic sewing machine by being taught
to identify which circuit boards/relays/switches have failed and need replacing.

So to be clear, I understand that ‘KY57/KY58 Cryptography School’ is either for teaching
how to set and operate the device (Operator Technician), or how to maintain and repair
the device (Repair Technician) – NOT how to design or reverse engineer whichever
cryptographic method(s) different devices can use to encipher information.

You would probably have to seek the advice of someone who was trained as a U.S. Army
or Marine Corp radio operator, preferably from the late 1980’s onwards, so you can be
comfortable that what I am asserting is correct.
Cheers

After doing some research and reading some other obituaries, I think you are right. A lot of the names I came across had obituaries for states on the east coast. Most of them were only in the bay area for a couple of years before being stationed elsewhere.