The Zodiac Killer gave us a map code on June 26th 1970, stating the "map coupled with this code will tell you where the bomb is set." To this day no bomb has been unearthed and the threat was likely an idle one, designed primarily to create fear within the American community. However, the map and code were real, and the answer to both has probably been sitting in plain sight for nearly fifty years. The Zodiac, aware that the '32 Symbol' cipher was unable to be broken because it had 29 different characters, gave us all the answers one month later when he mailed the July 26th 1970 'Little List' letter.
The numerous suggested bomb threats were all mailed to the San Francisco Chronicle, so it was evident that his threats were focused on San Francisco itself - which is why the Mount Diablo map included San Francisco and Vicinity rather than just the area around Mount Diablo. The 'Little List' letter was replete with all the information required to crack his map code.
In the 'Button Map and Code' letter the author gave us the "map coupled with this code will tell you where the bomb is set," and just one month later, clearly told us that the code "concerns Radians & # inches along the radians" Therefore, the code will at least contain the words "radians" and "inches" in the answer - and that may very well be the case. In fact, it tells us exactly where the intended bomb was to be set, within the design of the crosshairs with the bold black circle. With the threats geared towards schoolchildren and police it is apparent that these are the likely targets. The reference to SFPD = 0 being incorporated within the crosshairs, along with an accentuated black, bold zero suggesting a location, should be the biggest clue of all. His intended target was the San Francisco Police Department - the location of which can be found within this bold circle. 
The Zodiac Killer referenced "radians" and "inches" (not parts of radians and inches), so with probably just the use of a ruler back in 1970 the Zodiac Killer would measure his intended target this way. Therefore, if he is one eighth of an inch off in his measurements we can forgive him this textual indiscretion. Fortunately, we have Google maps, so the task is much easier.
With an intended target in San Francisco, there is only one answer possible to the "radians" and "inches" conundrum, and it's governed by geography. 1 radian = 57.3 degrees, 2 radians = 114.6 degrees, 3 radians = 171.9 degrees, 4 radians = 229.2 degrees and 5 radians = 286.5 degrees. This is detailed crudely on the map below.
It is apparent that Zodiac wasn't referring to 5 radians, as a line subtended from Mount Diablo at this angle would pass north of San Francisco. The same applies to 3 radians which runs parallel to San Francisco. Therefore, the answer has to be 4 radians or 229.2 degrees. The lines drawn below are only approximations, so are not pinpoint. 4 radians or 229.2 degrees passes over San Francisco somewhere in the vicinity of the airport - but this isn't the answer. If we add back the magnetic north value of 17 degrees in 1970, it equals 246.2 degrees. After all, Zodiac stated on the map, it was "to be set to Mag.N." 
How do we know 246.2 degrees is the correct angle to be subtended from Mount Diablo? The answer is simple - Zodiac told us so. Place the crosshairs above over a compass rose. A line subtended from the center of the compass rose passes exactly through the center of the bold black circle. In other words, the bold black circle is positioned at 246.2 degrees around the crosshairs. This is 4 radians + 17 degrees (magnetic north). Now all we have to do is find the inches subtended along the 246.2 degree line. This is even easier.     

The map scale is 6.4 miles to the inch, so the geography of San Francisco is self-constraining.
It is approximately 26.5 miles to the eastern edge of San Francisco from Mount Diablo (using the angle of 246.2 degrees).
4 inches would equal 25.6 miles, therefore, 4 inches subtended from Mount Diablo would land in the sea. Unless the Zodiac Killer had a submarine to bury his bomb this is not very likely.
It is approximately 34 miles to the western edge of San Francisco from Mount Diablo (using the angle of 246.2 degrees). 
6 inches would equal 38.4 miles and again would land in the sea.
Therefore, the answer has to be five inches along the 4th radian (plus magnetic north of 17 degrees). If this lands over the San Francisco Police Department we are in business. But first, we shall fill in the '32 Symbol' code using the words or clue given by the Zodiac Killer in the July 26th 1970 'Little List' letter.  
The section below is almost the complete solution to the '32 Symbol' cipher. Note how the Zodiac Killer inserts a hashtag style character between the "&" and "inches", with an arrow pointing between these two pieces of text. He is telling us to insert something here. We know from the above calculation it must be five inches, thereby completing the phrase:
"P.S The Mt.Diablo code concerns Radians & five inches along the radians"
​

The Zodiac Killer wasn't totally accurate, because the phrase should have read "P.S The Mt.Diablo code concerns Radians & five inches along the radian". The five inches to be subtended along the 4th radian (plus magnetic north) = 246.2 degrees. 
There are only three repeating characters in the code below, the triangle, the letter C and the letter O. With the inserted solution, these three characters are now represented by R, A, N, N, E and N. 

It was there in the Zodiac Killer's words all along; "The Mt.Diablo code concerns...... Radians & inches along the radian"
The last thing we have to do is place the large crosshairs with the black circle over the map of Mount Diablo, San Francisco and Vicinity. The location where the intended bomb was to be set should be 246.2 degrees and 5 inches subtended along a line drawn from Mount Diablo. It should also land over something to do with the San Francisco Police Department. Bearing in mind this was 1970 and the Zodiac Killer was using a ruler over a map, one eighth of an inch or so would be an acceptable margin of error, based on a map scale of 6.4 miles to the inch. The center and style of the black bold circle may be representative of a designer who intended the target to fall within this circle.  
There was no room on the map below, but we can see that if the superimposed crosshairs were expanded over the city of San Francisco, the center of the bold black circle subtended at 246.2 degrees for 5 inches would fall over the San Francisco Police Department at Ingleside Station. 
Ingleside Police Station is 31.06 miles from Mount Diablo. There are 6.4 miles to the inch. So Ingleside is 4.85 inches along the subtended angle of 246.2 degrees. Allowing for the leeway of crude measurement, this is 97% accurate in respect to 5 inches over the distance involved. This is why the Zodiac Killer placed SFPD next to the bold circle - it represented zero in mocking fashion, but more crucially, it represented the location of where the bomb was intended to be set - Ingleside Station or somewhere close by.              

Richard Radetich, the fallen officer, possibly referred to in the Zodiac Killer 'Button' letter was initially assigned to Ingleside Police Station, before moving to Park Station and eventually to Accident Investigation.

In analyzing the 'Button' letter map and code mailed on June 26th 1970, it is imperative we take a close look at the Zodiac Killer correspondence in the preceding few months to this communication for any clues to his mindset and intentions. There will be no definitive solution to the 32 symbol code presented here, although a location for where his bomb was 'to be set' can be argued with confidence, using four pieces of Zodiac material.
On April 20th 1970 the killer mailed 'The My Name is..Cipher' and stated "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station.  Even though I talked about killing school children with one. It just wouldn't doo to move in on someone else's teritory.  But there is more glory in killing a cop than a cid because a cop can shoot back." The Zodiac Killer was referring to the murder of San Francisco police officer Brian McDonnell on February 16th 1970, two months earlier, when a bomb exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. See here. 
He would back up this correspondence with the 'Dragon Card' just one week later on April 28th 1970 declaring "I hope you enjoy yourselves when I have my blast." This card featured elements of the book Don Quixote, a novel by Miguel de Cervantes Saavedra, in which Alonso Quijana, a prolific reader of books, became so mesmerized by the chivalry contained within them, that under the assumed name of Don Quixote, along with his squire Sancho Panza, began a quest to revive this virtue. What the Zodiac Killer was inferring with this particular card can be debated, but the 1899 Waller Street Police Station is situated on the boundary of the San Francisco Golden Gate Park and in close proximity, also situated in the park, is the memorial statue of Miguel de Cervantes, featuring Don Quixote and Sancho Panza. Was the Zodiac Killer insinuating an attack close to the police station and park, similar to the murder of police officer Brian McDonnell.  

Then on June 26th 1970 this communication arrived, insinuating the murder of another police officer, Richard Radetich (25). On June 19th at 5.25 am he was gunned down by three shots from a .38 caliber revolver at point blank range through the driver side window of his vehicle, while in the process of serving a parking ticket by 643 Waller Street, San Francisco, in the Lower Haight District and subsequently died 15 hours later. The murder of Richard Radetich, as of writing, remains unsolved.
​The Zodiac Killer appeared to be heavily centering his focus in the Haight District. The statue in the park, 1899 Waller Street and 643 Waller Street all fall within a 2 mile radius, featured through three consecutive mailings.
It is therefore this locality of San Francisco we shall again turn our attention to, when considering where the Zodiac Killer may be directing his threat towards in the Button letter, using recent history to predict the future.
There is good reason to believe the Zodiac Killer was threatening an attack on Ingleside Station-San Francisco Police Department, located at 1 Sgt John V Young Lane, named in honor of Sgt. John Young, killed by gunmen in 1971 after they stormed the police station. Ingleside Station is 4.6 miles south of 1899 Waller Street. The Zodiac Killer never followed through on many of his claims, but this may very well be the location he was threatening to bomb on June 26th 1970. So here is the evidence.
When the Zodiac Killer mailed the Button letter, it was accompanied by a Phillips 66 road map and his crosshairs, stating they were "to be set to Mag.N." That is magnetic north, calculated at 17 degrees in 1970. Clearly he soon realized that the information or code he supplied, coupled with the Phillips 66 map, was insufficient to crack the cipher or determine a location for the bomb. One month later he rectified the problem with the Little List letter mailed on July 26th 1970, when he incorporated two further crosshairs, with all the clues we needed.     

This was the first crosshair on the right.
The Zodiac Killer continually taunted police with his running victim total, always attributing the police with zero. This was nothing new. However here he deliberately brings attention to the zero, marking it noticeably darker, as though it has increased significance. It is also placed within the crosshairs, indicating an area within his sights.
Bearing in mind the acronym SFPD, it is clear he has the San Francisco Police Department firmly focused as his target. That police department, we will attempt to show, was Ingleside Station located just off Balboa Park at San Jose Avenue.
The Zodiac Killer sent us a second set of crosshairs in the Little List letter stating "PS. The Mt Diablo code concerns Radians + inches along the radians."
This was the clue we needed.
In a previous article we highlighted a region of San Francisco for particular interest, using the following technique, but with improved map plotting and examining carefully the Phillips 66 map, it has become apparent the amended focus should be squarely over Ingleside Police Station.
The phrase "PS. The Mt Diablo code concerns Radians + inches along the radians," clearly tells us to use radians as our degrees from the north axis and is "to be set to Mag.N."  So we are looking for whole radians, to which we then add in the magnetic north value of 17 degrees. This will give us our angle on the Phillips 66 map.
The​ bold circle above is sitting between the 180 and 270 degree axis. In fact the center of the bold circle is positioned at 246 degrees. This can be confirmed using a compass rose. One radian is valued at 57.296 degrees, so four radians are valued at 4 X 57.296 = 229.184 degrees. Add in the magnetic north value of 17 degrees and our final total is 246.184 degrees.
The Zodiac Killer was indicating four radians + magnetic north. He never incorporated this into the Button letter code and Phillips 66 map, telling us the crosshair was to be set to magnetic north, but a month later in the Little List letter, he added the magnetic north value in for us, seen by the positioning of the bold circle next to SFPD. Four radians and 17 degrees is 246 degrees. This bold circle is also positioned at exactly 246 degrees (see below). 

This compass rose and SFPD crosshair, angled at 246 degrees can now be placed over the Phillips 66 map. But first we will examine the second  crosshair placed at the foot of the Little List letter.
The Zodiac Killer placed 'Diablo', the Spanish word for devil over the 180 degree axis. This may not have any significance, but if we couple the 66 from Phillips 66, with the number 6 on the Phillips map crosshair, we get 666, the number of the beast. By using the same method we can add the number 66 to the 180 degrees and arrive at 180 + 66 = 246 degrees once more.
Whether this was by design however, is open to question.
Let us now go ahead and superimpose the compass rose and SFPD crosshair over the Phillips 66 map (below).
To be completely accurate, both have been tilted by three degrees to match the original Zodiac crosshair. (shown here).
246 degrees takes us, as the crow flies, 31 miles southwest, passing directly over Ingleside Station-San Francisco Police Department (SFPD). The map scale is 6.4 miles to the inch, so if we were traveling inches along the radians, it would be 4.84 inches.  
If we round off, the phrase "PS. The Mt Diablo code concerns Radians + inches along the radians," would become: "PS. The Mt Diablo code concerns four Radians + five inches along the radians." That is 229 degrees, but set to magnetic north gives us the 246 degrees shown in the diagrams. 

The Button letter code however, as mentioned above, would not incorporate the exact angle or directions to Ingleside Station. Remember the Zodiac Killer stated "The Map coupled with this code will tell you where the bomb is set."
The map crosshair told us to "set to Mag. N", which was 17 degrees. So if the code had an angle within it, this angle would be 229 degrees (before it is coupled with the map).
With 29 unique characters in the 32 symbol code, simple substitution is not an option. Some form of key must be unearthed.
Below are two incorrect examples of what we may be looking for. The first example matches all the repeating characters, even the dotted circle, but makes no sense. The second is more recognizable as a logical sentence, but matches little within the code. You may have a better solution. 
Ingleside Police Station may very well have been the target of the Zodiac Killer, but without breaking the code, it will remain a possibility rather than a proven fact. Thank you for your time. 

This topic has been discussed before in the article 'Mount Diablo-The Devil is in the Detail', however here we will hopefully finalize the story with the last piece of the jigsaw. The Zodiac Killer mailed us the Button Letter and Phillips 66 Petroleum Map on June 26th 1970 stating "The Map coupled with this code will tell you where the bomb is set. You have until next fall to dig it up."  Then one month later he mailed the Little List Letter on July 26th 1970, giving us a further cross-haired diagram and the phrase "PS. The Mt. Diablo Code concerns Radians & # inches along the radians." This was basically a further clue to push us in the right direction. 
​The first thing to look at is the Phillips 66 Map crosshair with numbers around its cardinal points, the number 0 facing north, the number 3 on the east axis, the number 6 on the south axis and finally the number 9 on the west axis. It is easy to consider these as clock points, however the number 12 is replaced by a zero, so we will refrain from doing so. But what relevance do these numbers have, bearing in mind we are looking for a grid position on where the bomb is set and considering a clock face does not begin on zero. The Zodiac mentioned 'radians and inches along the radians,' we know a radian to be valued at 57.296 degrees, so all we have to do is travel around the circumference of his crosshair situated over Mt Diablo, by a fixed number of radians. Then once we have found the correct amount of radians, we travel away from that point, along the radian in inches, until we locate the bomb. But how many inches. The only numbers we have are the ones Zodiac placed around the crosshair, and these are situated along the radian line, so these are what we'll use to formulate the answer.

On the right is the diagram the Zodiac Killer supplied us with in the Little List Letter, superimposed on a compass rose to find the angle of the bold circle. The Zodiac mentioned radians, not part of a radian, so we are dealing in whole amounts of 57.296 degrees. The Zodiac also wrote next to the crosshair on the Phillips 66 Map; "is to be set to Mag N." This meant Magnetic North, calculated at approximately 17 degrees in 1970. 4 radians = 4 X 57.296 = 229.184 + 17 degrees = 246 degrees. The bold circle the Zodiac gave us, shown in the diagram, is positioned at exactly 246 degrees. We now have the angle, so let us move to the second part of the equation, 'concerning inches along the radians.' The 246 degree line has to be given a number, in relation to the numbers Zodiac placed around the crosshair on the Mount Diablo Phillips 66 Map. Using the concept of 12 divisions of 30 degrees to form a whole circle of 360 degrees, what does 246 degrees represent. The number 3 the Zodiac gave us sits at 90 degrees, the number 6 sits at 180 degrees and the number 9 at 270 degrees, so 246 degrees would rest at 246 divided by 30.

246/30 =8.2. This gives us a quantifiable amount of inches to travel away from Mount Diablo. Don't forget the Zodiac gave us the phrase "PS. The Mt. Diablo Code concerns Radians & # inches along the radians."  The only place on the Phillips 66 Map where inches are mentioned, is in the grid scale at bottom left of the map, under where it states 'San Francisco and Vicinity.'  The scale states 'one inch equals approx 6.4 miles.'
We have 8.2 inches, so with a simple calculation we multiply 8.2 by 6.4, to give us our distance to travel away from Mount Diablo.
8.2 X 6.4 =52.48 miles. In other words the bomb is set 52.48 miles from Mount Diablo at an angle of 246 degrees. But bear in mind the Zodiac stated "The Map coupled with this code will tell you where the bomb is set. You have until next fall to dig it up."
So the code of 32 symbols has to tie in with this location.
Below is a diagram with an angle of 246 degrees radiating from from Mount Diablo, you will notice it passes over the bold circle Zodiac drew and lands in the area of San Francisco International Airport. In fact it is virtually 52.48 miles on Google Maps to this location. Here is the area of South Linden Avenue, right next to San Francisco International Airport, shown as being 52.90 miles from Mount Diablo.   

The next thing to do is look at the 32 symbol cipher the Zodiac constructed, and his statement "The Map coupled with this code will tell you where the bomb is set. You have until next fall to dig it up." It is my guess that the code is giving us a location and the red line of 246 degrees on the map above will bisect that location point. The only notable location we have unearthed is somewhere very close to San Francisco International Airport, so let us start with that.   

San Francisco International Airport is exactly 32 letters, like the code. But of course this is not conclusive. We have one other slight discrepancy, in that San Francisco International Airport is 31.15 miles from Mount Diablo as the crow flies. It is just a matter of what the Zodiac actually meant when he referred to "The Mt. Diablo Code concerns Radians & # inches along the radians." Was it meant literally in a direct line, or by using the map scale designed to give us our shortest traveling distance to the bomb location from Mount Diablo, using the 246 degree line as our guide. Was the use of the word 'concerns' to imply a less than literal translation. Setting a bomb close to the airport would certainly be a daring target for the Zodiac Killer, if it was ever to be set at all.

​http://www.zodiacciphers.com/zodiac-news/mt-diablo-the-devil-is-in-the-detail

In a recent article we examined the Mount Diablo code in conjunction with the Phillips Road Map and suggested a possibility that the Zodiac 32 Symbol Cipher may have revealed San Francisco International Airport, situated at 4 radians or 229 degrees from Mount Diablo, but coupled with the Magnetic North value of 17 degrees at the time of mailing, was to give us a final value of 246 degrees, exactly corresponding with the bold circle the Zodiac Killer provided within his crosshair on the Little List Letter he mailed on July 26th 1970.  View initial article (Part One). View Part Two.
This final part of the trilogy attempts to cement the motivation behind the Zodiac Killer's crosshairs he gave us on the Phillips 66 Road Map as part of the Button Letter mailed on June 26th 1970 and the Little List Letter one month later on July 26th 1970. In the following diagram we have incorporated the three crosshairs together to better explain the findings. This idea has been covered before, but finalizes the three part story under one banner in a little more detail.

The Zodiac Killer stated on the Button Letter 'The Map coupled with this code will tell you where the bomb is set'. In other words the two are to be used in conjunction with each other. This is what we did in the earlier articles, taking the code of San Francisco International Airport at 229 degrees and coupling it with the map, set at a Magnetic North value of 17 degrees, to arrive at the final value of 246 degrees.
However this would not have been possible using the Button Letter and Phillips 66 Road Map alone. The Zodiac realizing this gave us the two additional crosshairs on the Little List Letter, with a couple more hints. Firstly the bold circle and secondly the phrase 'PS The Mt Diablo code concerns Radians + inches along the radians'. The Zodiac Killer however placed this phrase over the crosshair itself, when he could have easily accommodated both elements separately, unless he had an ulterior motive.
The phrase runs over the lower north-south axis; to be precise over the 180 degree axis or number 6 on the Zodiac dial. In fact only the word Diablo is bisected by this line. 
Let us expand upon the 'Map coupled with this code will tell you where the bomb is set' to better explain things, using this phrase 'The Phillips 66 Map coupled with this code will tell you where the bomb is set'.
In the first instance the code of San Francisco International Airport or 229 degrees was coupled with the map set at Magnetic North of 17 degrees to equal 246 degrees. The Mount Diablo code was written on the 180 degree axis, so we will couple this 180 degrees with the map or more specifically the Phillips 66 Map, to give us 180 + 66 = 246 degrees, the exact position of the bold circle he provided us in the Little List Letter and exactly the same as 4 radians and 17 degrees. Then we shall take the number 6 he provided on the 180 degree axis and once again couple this with the Phillips 66 Map to give us 666, the mark of the Devil or Diablo. The conventional view is that the peak derives its name from the 1805 escape of several Chupcan Native Americans from the Spanish in a nearby willow thicket. The natives seemed to disappear, and the Spanish soldiers thus gave the area the name "Monte del Diablo", meaning "thicket of the devil."
Diablo was placed over the 180 and 6 axis and on both occasions coupled with the 66 from the Phillips 66 Road Map gave us something significant, but whether or not this was his true intention is still unclear and may never be resolved. 

In a recent article we examined the Mount Diablo code in conjunction with the Phillips Road Map and suggested a possibility that the Zodiac 32 Symbol Cipher may have revealed San Francisco International Airport, situated at 4 radians or 229 degrees from Mount Diablo, but coupled with the Magnetic North value of 17 degrees at the time of mailing, was to give us a final value of 246 degrees, exactly corresponding with the bold circle the Zodiac Killer provided within his crosshair on the Little List Letter he mailed on July 26th 1970. Here we will take this one step further and see where the adjustment of the Magnetic North value of 17 degrees takes us from the airport location and see if the pinpointed location makes any sense in respect to all we think we know about the Zodiac Killer. View initial article (Part One).  

It is difficult to be exact using the Zodiac diagrams, but the angle of 246 degrees passes over the Bayview-Hunters Point region of San Francisco, situated only 5.5 miles from the Mason and Geary intersection, where it is believed Paul Stine picked up the Zodiac Killer on October 11th 1969.
Passing through the Bayview area is 3rd Street and close by is Highway 101, two possible routes Paul Stine may have traveled on his return back from San Francisco International Airport after dropping off his final paying fare and returning back to the San Francisco theater district. The Bayview-Hunters Point region has a colorful history and has been the scene of much controversy and conflict down the years. 
After a San Francisco ordinance in 1868 banned the slaughter and processing of animals within the city proper, a group of butchers established a "butchers reservation" on 81-acre of tidal marshland in the Bayview district. Within ten years, 18 slaughterhouses were located in the area along with their associated production facilities for tanning, fertilizer, wool and tallow. The "reservation" (then bounded by present-day Ingalls Street, Third Street, from Islais Creek to Bayshore) and the surrounding houses and businesses became known as Butchertown. The butcher industry declined following the 1906 San Francisco earthquake until 1971 when the final slaughterhouse closed.
Taken from Wikipedia
If we insert a Zodiac timeline to this, the final slaughterhouse closed in 1971, the year the Zodiac mailed us his second to last confirmed correspondence on March 13th 1971, before he went on sabbatical for close to three years, although not suggested, the irony cannot be ignored. Also from our experience the undeniable suggestion the Zodiac Killer may have served in the military or have naval connections has been a constant. The Zodiac timeline is not certain, on account of earlier murders that may or may not be attributed to him, such as the Riverside murder of Cheri Jo Bates on October 30th 1966, nevertheless this is where we will start.  

Is there anything that ties Riverside, the Vallejo and Benicia areas and Bayview-Hunters Point in San Francisco. Well not exactly, but it doesn't hurt to explore one option.
The Long Beach Naval Shipyard, which closed in 1997, was located at Terminal Island between the city of Long Beach and the San Pedro district of Los Angeles and approximately 23 miles south of the Los Angeles International Airport. It was situated 1 hr 20 minutes drive west of Riverside. The Mare Island Naval Shipyard is located in Vallejo, the hot zone highlighted by Kim Rossmo, when using the art of geographical profiling to zoom in on a possible home location of the Zodiac Killer. And finally the Hunters-Point Naval Shipyard, San Francisco, located on 638 acres in the southeast corner of the city. At the start of World War II the Navy recognized the need for greatly increased naval shipbuilding and repair facilities in the San Francisco Bay Area, and in 1940 acquired the property from the private owners, naming it Hunters Point Naval Shipyard. The property became one of the major shipyards of the west coast. It was later renamed Treasure Island Naval Station Hunters Point Annex. During the 1940's, many workers moved into the area to work at this shipyard and other wartime related industries.
The key fissile components of the first atomic bomb were loaded onto the USS Indianapolis in July 1945 at Hunters Point for transfer to Tinian. After World War II and until 1969, the Hunters Point shipyard was the site of the Naval Radiological Defense Laboratory, the US military's largest facility for applied nuclear research. The yard was used after the war to decontaminate ships from Operation Crossroads. Because of all the testing, there is widespread radiological contamination of the site. After the war, with an influx of blue collar industry, the area remained a naval base and commercial shipyard. The Navy operated the yard until 1974, when it leased most of it to a commercial ship repair company. Extract from Wikipedia. 
The Navy ceased operations in 1974, the year the Zodiac mailed his final confirmed letter, the Exorcist Letter on January 29th 1974, in fact three further potential Zodiac letters were mailed that year, before the Zodiac Killer finally disappeared for good.

The Zodiac letters definitely switched emphasis after the Paul Stine murder on October 11th 1969, from the November 9th Bus Bomb Letter through to the Little List Letter on July 26th 1970, making references to the murder of two San Francisco police officers, Brian McDonnell on February 16th 1970 and Sgt Richard Radetich on June 19th 1970. Bombing was definitely on the agenda, although it was believed he never followed up in any of his proposed threats. 
The question remains, was irony his intention, if he had indeed selected Hunters Point as a location, somewhere he may have been familiar with or even worked. Even the surrounding areas were once known as 'Butchertown'.
In fact a bombing did occur in the January of 1970 at Hunters Point Police Station, highlighted in this KPIX eyewitness report and although with near certainty not the Zodiac Killer, it is possibly something he may have been aware of, had he worked in this region of San Francisco.
Did the Zodiac Killer live and work in San Francisco during the majority of his crimes, placing distance between himself and the first three attacks, before coming home to roost or did he live across the bay in the Vallejo/Benicia area and only used San Francisco as a mailing point for the most part. Who knows for sure.
But the 246 degrees from the center point of Mount Diablo runs directly across the Hunters-Point Naval Shipyard, in the Bayview District, notwithstanding the accuracy of the Little List diagram and the Mare Island Naval Shipyard has always courted some attention in Zodiac circles, on account of the proposed naval connection to our killer. Did he work at both facilities or even the third at Riverside. Was irony at work here or is the Hunters-Point connection just simply wide of the mark once more. 

SEE PART THREE -  http://www.zodiacciphers.com/zodiac-news/sfi-airport-hunters-point-part-three

The Zodiac Killer after killing four people in Benicia, Vallejo and Napa, suddenly switched the emphasis to the heart of San Francisco, mailing a letter to the San Francisco Chronicle on October 13th 1969, promising to target a school bus and 'pick of the kiddies as they come bouncing out.'  Following this came multiple references to bombs, notably in his 'My Name is.. Cipher' detailing a bus bomb diagram and suggesting he was not responsible for wiping out 'that blue meannie with a bomb'. He was detailing the murder of San Francisco police officer Brian McDonnell on February 16th 1970, two months earlier, when a bomb exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. The Zodiac Killer then mailed the Dragon Card on April 28th 1970 stating 'I hope you enjoy yourselves when I have my blast', followed by the Button Letter cementing his connection to San Francisco by part referencing the murder of a man in a parked car, thought to be police officer Richard Radetich outside 643 Waller Street and sending an attached Phillips 66 Road Map, stating 'the map coupled with this code will tell you where the bomb is set'. Then on July 26th 1970 the Little List Letter was mailed, including two crosshairs, one with a prominent black circle including the acronym SFPD = 0 and the second referring us back to the Button Letter, stating 'The Mt Diablo code concerns radians + inches along the radians.' The emphasis appeared squarely over the region of his final murder, that of Paul Stine on October 11th 1969, so was the bomb the Zodiac Killer promised us, to be found somewhere in San Francisco, after all the Phillips 66 Road Map was entitled San Francisco and Vicinity.       

The Zodiac Killer mentioned radians (an angle of measurement), of which one radian is valued at 57.296 degrees. If we look at the prominent black circle he gave us on the Little List Letter, its center falls over 246 degrees on a compass rose. (see right).
246 degrees is 4 radians + 17 degrees.
When the Phillips 66 Road Map was mailed on June 26th 1970 Magnetic North was approximated at just under 17 degrees. 
4 radians = 4 X 57.296 = 229.184 + 17 degrees = 246 degrees.
So apparently the Zodiac Killer was very familiar with radians and the value of Magnetic North, unless we are assuming he was just lucky in his placement of the bold circle on the diagram. His further reference to SFPD next to this circle, makes one think this is where we should be centering our focus.
The final confirmed murder of the Zodiac Killer was that of Paul Stine at Presidio Heights on October 11th 1969 and in his letter mailed one month later on November 9th he again ridicules the police and lays out the details for his construction of a bomb.
Paul Stine had picked up his final paying fare that night from Pier 64 to the Air Terminal at San Francisco International Airport, before returning back to the theater district near the Mason and Geary intersection. This is where it is believed he picked up the Zodiac Killer for one last fateful journey. 
We know the Zodiac Killer mentioned radians and inches along the radians, so let us start with complete radians. We know from above that the value of 4 radians is significant, so this being 229 degrees, we shall place a compass rose over Mount Diablo and see where this takes us, in respect of San Francisco. 

It can be seen that 229 degrees falls on the south edge of San Francisco International Airport by Old Bayshore Highway. 
Was the Zodiac Killer intending to ratchet up the fear by exploding bombs in the vicinity of the airport. Of course this hypothesis is just pure speculation, or is it. Let us take a further look at the Button Letter mailed on June 26th 1970, where the Zodiac Killer stated 'The Map coupled with this code will tell you where the bomb is set. You have until next Fall to dig it up,' and enter something alongside the code.

San Francisco International Airport is exactly 32 letters long and fits squarely alongside the 32 symbol Button Letter code. However the 246 degree mark falls somewhere between the Mason and Geary intersection and San Francisco International Airport, an area all too familiar with the Zodiac Killer. Was the bomb to be set according to the code above, but coupled with the map set at Magnetic North of 17 degrees, was to give us a directional location of 17 degrees due west of San Francisco International Airport, to arrive at a final value of 246 degrees he so precisely gave us in the Little List Letter on July 26th 1970. 

SEE PART TWO - http://www.zodiacciphers.com/zodiac-news/sfi-airport-part-two-hunters-point

The Zodiac Killer mailed the Button Letter to the San Francisco Chronicle on June 26th 1970. In this letter he boasted about his ability to annihilate a school bus, as well as claiming he had shot a man in a parked car, but in addition to this, he accompanied the Button Letter with a Phillips 66 Road Map of the San Francisco Bay area and vicinity. On this map he had added the Zodiac crossed circle, with the numbers 0,3,6 and 9 at the four cardinal points of North, East, South and West respectively. He added the text 'is to be set to Mag.N.'  The Zodiac Killer claimed that this map, coupled with a code he provided, would tell us where a bomb was set. Unfortunately it has been widely accepted that the details the Zodiac Killer provided were too vague to pinpoint any realistic location.
In this article we will examine the possibility, that the Zodiac Killer gave us far more than we had first imagined. He realized that the Button Letter correspondence was insufficient, so quickly followed this up, with the Little List Letter one month later on July 26th 1970 to nudge us in the right direction. These two letters were as intertwined as could possibly be and it all started with his choice of Mount Diablo as the focus and his selection of the Phillips 66 Road Map itself.
The first part of this explanation might seem rudimentary and have you running for the off switch, but a lot more will follow.
So far, through fifteen articles, it has been demonstrated that the Zodiac Killer had an agenda, based on his twisted concept of religion. He also with near certainty had a flair for mathematics and the dramatic and this became apparent in much of his correspondence. The one thing he needed was a code he could utilize, to encipher his message throughout, and this formed the basis of a key inspired by Genesis and the six days of creation. This was most apparent in the 13 Symbol Cipher he sent to authorities on April 20th 1970.  http://www.zodiacciphers.com/1/post/2013/06/the-kane-cipher.html
So far this code key has been shown to consistently work, when applied to at least ten of the Zodiac Killer's most cryptic cards and letters, including the three unsolved ciphers. 
For the full story and a full list of articles based on this concept, links have been placed at the foot of the page.      

(See diagram above right). To show the reasoning behind this simplistic arrival at the number 666, by combining the Phillips 66, with the number 6 at the foot of the crosshair, we have to move forward one month to the mailing of the Little List Letter on July 26th 1970.
The Zodiac Killer, aware that Button Letter and Phillips Map provided insufficient material, gave us a second clue at the foot of the Little List Letter.

The next section is from a previous article, but is very relevant to show that adding the Phillips 66 number, to form the 'number of the beast' in the South position has some logic. To save time this article will now be placed here in its entirety.
The Button Letter was mailed on June 26th 1970, containing a footnote that stated ' The map coupled with this code will tell you where the bomb is set. You have until next fall to dig it up '. But no bomb or any other relevant location was discovered. The 340 Cipher remained crackproof, the 13 Symbol Cipher appeared on the face of it, simply too short for any meaningful decryption and by late July of 1970 this new 32 symbol code sent with the Button Letter, along with the attached Phillips Road Map provided little relief for an audience on the wane.

Previously we added the Phillips 66 number, to the number 6 on the South axis to arrive at 666.
Immediately above we demonstrated that 246 degrees was the angle shown on the Little List Letter.
The South position on the Zodiac circle or crosshair is at 180 degrees.
Now add the Phillips 66 number once again, but this time to the 180 degrees.(the number 6 position). 180+66 = 246 degrees.
Therefore 246 degrees can be found using two different methods, both, with different clues the Zodiac Killer gave us, indicating this angle as the most likely direction of our so called bomb or mystery location. The Phillips 66 Map was almost certainly chosen with this specific reason in mind and the whole concept began in a name, that of Mount Diablo.
In a previous post http://www.zodiacciphers.com/1/post/2014/04/the-three-unsolved-ciphers-linked.html, all three unsolved ciphers could be linked through the figure 888, the Hebrew gematric total for the name Jesus. See Wikipedia.
The Button Letter code added up to 444, as did the 13 Symbol Cipher in both standard English gematria and the Zodiac code based on Genesis and the six days of creation. These combined as explained in the previous post totaled 888, a number that was also shown to be present in the final row of the 340 Cipher. 
Incidentally, LUCIFER in standard English gematria (ie: A=1, B=2, C=3, D=4 etc) = 74, but applying the key number 6, shown on the Phillips 66 Map, Lucifer = 74 x 6 = 444 and that crucial number once more. Try out on gematric calculator.
The 13 Hole Postcard was crucial to giving us the key number 6, when the Zodiac Killer wrote 'There are reports city police pig cops are closeing in on me, FK I'm Crackproof, What is the price tag now'.
Simply, F is the 6th letter of the alphabet and the 6th letter on the 13 Symbol Cipher is K, giving us FK I'm Crackproof. To understand this concept visit  Symmetry of the 13 Symbol Cipher.  It has also been shown that the letters FK in the gematric code below are represented by the figure 63, the exact number of symbols present in the 340 Cipher. So the number six was relevant to the 13 Symbol Cipher, as possibly a key, and one that was integral, in the linking of all three unsolved ciphers. SEE HERE. 
If you then revisit the 340 Cipher, the FK is positioned either adjacent or diagonally exactly six times within the 340 character cipher, placing the number 6 key to all of the codes, inclusive and subsequent to November 8th 1969.

1+2+3 =  6           = 6
4+5+6 = 15 = 1+5 = 6
7+8+9 = 24 = 2+4 = 6   = 666
If we add the first set of bold figures we get 45. And 45 combined with 666 = 45666, the name of Jesus.
In fact, if we multiply the name of Jesus 4 x 5 x 6 x 6 x 6 = 4,320 and divide this by either the 12 disciples of Christ or the 12 signs of the Zodiac, we get 360 or the 360 degrees of the Zodiac circle.
However before the Zodiac Killer mailed both his Button Letter and Little List Letter to the San Francisco Chronicle, he sent us the Dragon Card, two months earlier, on April 28th 1970.             

In the New Testament, the dragon and serpent are frequently used to identify Satan or the devil. It can be seen in Revelation 12:9:  'The great dragon was hurled down - that ancient serpent called the devil, or Satan, who leads the whole world astray. He was hurled to the earth, and his angels with him' and Revelation 20:2: 'He seized the dragon, that ancient serpent, who is the devil, or Satan, and bound him for a thousand years'.
So the devil, religion and liberal sprinkling of mathematics, can now be linked through three letters in three months, all indicating the Zodiac Killer's intention of using a bomb in his arsenal of destruction and one that was to be placed exactly 246 degrees from the heart of evil, that of Mount Diablo.

The Button Letter was mailed on June 26th 1970, containing a footnote that stated ' The map coupled with this code will tell you where the bomb is set. You have until next fall to dig it up '. But no bomb or any other relevant location was discovered. The 340 Cipher remained crackproof, the 13 Symbol Cipher was simply too short for any meaningful decryption and by late July of 1970 this new 32 symbol code sent with the Button Letter, along with the attached Phillips Road Map provided little relief for an audience on the wane.

Gareth Penn proposed the Radian Theory to indicate how the Zodiac killer selected his crime locations, albeit slightly flawed, it was not without merit, as many theorists have proposed the idea that the Zodiac selected his victims based upon a specific geographical template, after all the author of the Button Letter on June 26th 1970 included a Phillips Road Map overlayed with the Zodiac crosshair symbol and the Bus Bomb Letter contained a crosshair, tagged with five X's on the circumference.
Also closely associated to the Radian Theory, is the thought that the Zodiac was may'be influenced by Pi, hence his choice of the word Zodiac as his moniker, and the crossed circle emblazoned on many of his postcards and letters.
Incidentally Pi is the ratio of a circles circumference to its diameter and valued at 3.14159265... or shortened to 3.14 for simplicity.

There are 4 large eyes in the main body of the card and 13 in total, 314 in reverse.
Now take a look at the word BOO, could it conceivably be possible that the B is a 1 and 3 in close proximity, to form 314 in reverse with the four eyes underneath. 
Then we have the strange symbol placed on the Halloween Card envelope and at the foot of the card once opened. This could be interpreted as ZVF, Zodiac Victims Fourteen or a host of other things. But lets take it as a numerical value. Firstly, the 4 dots as simply the number 4, then the rest as a joined 7 and F. With F being the 6th letter of the alphabet and the fact it is joined to the 7, we shall proceed with its sum total of 13, to form 413. We now have 314 in reverse yet again.
It dosen't stop there as we shall see. Many observers have speculated why the Zodiac chose to reverse the letter N, when he wrote BY KNIFE on the back of the Halloween Card. Well N is the 14th letter of the alphabet and immediately right of it, is the letter C, contained in the word DICE, and C is represented by 3 numerically to form 143, but of course the N is reversed, so we have to flip 14 to get 41, thereby creating 413 and pi in reverse once more. And the letter P is further to the right, part of the text BY ROPE, is it stretching a bit too far to believe this stands for pi.
The 4 quadrants of death, separated by the 13 letters of  PARADICE and SLAVES could have been pointing us to the fact that Pi was the Zodiac symbol all along, but then again it could mean absolutely nothing.