Recently a new site, Zodiac Killer Theory has come to my attention courtesy of its creator Marcelo Leandro, from Laranjeiras do Sul - Paraná, Brasil, currently working for the Instituto Nacional do Seguro Social and is a site primarily devoted to Zodiac theories, as the name alludes to.
Clearly he has devoted a lot of time and effort formulating many unique ideas relating to a multitude of Zodiac correspondence, including the 408 Cipher, Halloween Card, 32 Symbol Cipher and more. If new and fresh ideas are what you want, this is a good starting point. It is always refreshing to see that the Zodiac enigma stretches far beyond the country of its origin, and it is this worldwide interest that gives hope, that one day the case may finally be cracked.
To visit Zodiac Killer Theory : http://zodiacode1933.blogspot.co.uk/
This site also has an RSS Feed of latest posts and comments, to keep you up to date the moment anything is posted or you can visit World News or Zodiac RSS Feed on this site for the latest updates also.

Although the last confirmed murder attributed to the Zodiac was the slaying of taxicab driver Paul Stine on October 11th 1969, the killer continued his onslaught towards the citizens of Northern California and beyond in the form of threatening and taunting letters to the newspapers, the like of which authorities had never experienced previously and governed by an overwhelming desire to keep the fear factor well and truly alive in the psyche of everyday people. Driven by the art of humiliation and misdirection, he led the investigative bodies on a piece of string, complimented by an inordinate amount of good fortune, to elude capture throughout his manifesto of evil during the late 1960s and early 1970s. Although his communications to the newspapers eventually dwindled away, it may be that two of his later letters, despite being shorter by comparison, held the biggest key to unraveling - or at the very least guiding us - into the footprints of a killer.

The Exorcist letter mailed to the San Francisco Chronicle on January 29th 1974 was closely followed just five days later by the SLA letter, postmarked February 3rd 1974 from Los Angeles. Both letters seemed to offer very little in the way of clues.
Kevin Robert Brooks steps into the mind of the Zodiac Killer, believing he is slowly drawing his suspect out of the shadows and into the light, as one and the same. On the face of it, little seems to stand out in these two short messages, until you compare these two letters alongside articles sent by Donald Lee Bujok to the Billings Gazette in the 1970s. In a previous article it was shown that Donald Lee Bujok had mailed numerous literary observations on various social issues of the day to the newspapers, giving us a tantalizing glimpse into the psyche of what drove him - and possibly indicated that the author was luring us into a game of 'cat and mouse', thereby toying with authorities to see if they could connect the dots between the Billings Gazette articles and the Zodiac communications that had streamed from the pen of a killer for nearly half a decade.   

One of the most interesting letters he sent to the Billings Gazette was his reference to The Exorcist film, dated June 2nd 1974, sent approximately four months after the Zodiac mailed the Exorcist letter to the San Francisco Chronicle on January 29th 1974. In the article he ridiculed the idea of possession and thoughts of the supernatural, not unlike Zodiac's statement at the top of the Exorcist letter, in which he wrote "I saw and think the Exorcist was the best satirical comedy that I have ever seen".

In the Billings Gazette he opened up with the statement "I have been reading and hearing all about the Exorcist in Billings", very similar to his superfluity of words in the Exorcist letter. On March 22nd 1974, in another letter to the Billings Gazette, he seemed irked by a Dick Tracy horror strip apparently promoting poor moral values, mirroring the Badlands/Citizen letter, mailed by the supposed Zodiac on May 8th 1974, just one-and-a-half months later. In the Citizen letter the author chastised the running of advertisements for the Badlands movie, stating "Sirs -- I would like to expression my consternation concerning your poor taste + lack of sympathy for the public, as evidenced by your running of the ads for the movie "Badlands", featuring the blurb: "In 1959 most people were killing time. Kit + Holly were killing people." In light of recent events, this kind of murder-glorification can only be deplorable at best (not that glorification of violence was ever justifiable) why don't you show some concern for public sensibilities + cut the ad?  A citizen". There was a further vitriolic letter aimed at columnist Marco Spinelli in the Red Phantom letter on July 8th 1974. Donald Lee Bujok, In another article, moralizes over the issues of hunting and the rights of landowners. 

However,  there is another more revealing piece of correspondence he mailed to the Billings Gazette, dated Monday March 17th 1975, entitled It could be the octane rating, which provided further and more interesting parallels to the Zodiac case, as well as to the apparently insignificant SLA letter, that will now become the centerpiece of our focus. 

The Zodiac presented us with symbols at the foot of the Exorcist letter, thought to be the words To Kill, as Kevin Robert Brooks surmised this was the most reasonable assumption based on what we know about the killer. He then, as a form of prompt to the police, mailed us the SLA letter just five days later - and in trademark Zodiac style, continued his art of toying with authorities by stating 

"Did you know that the initials SLA spell "sla", an old Norse word meaning "Kill". a friend" (even stylizing his 'K' in typical Mikado fashion). The SLA letter was postmarked February 3rd 1974. Just over one year later, on March 17th 1975, came more high octane correspondence in the form of a Donald Lee Bujok letter crafted on the subject of a haunted Volkswagen. It was titled by the newspaper "It could be the octane rating".

In the article he placed two interesting features that spiked interest. Firstly, he mentioned Mr Kolchak, the lead character from the television series Kolchak the Night Stalker. The first episode of which, is about a serial killer who writes to newspapers, entitled "The Ripper" and aired by ABC television on September 13th 1974.

The storyline is about a murderer who preys on women in Chicago, with Carl Kolchak played by Darren McGavin, strong in his belief that this was not a copycat, but actually Jack the Ripper himself - a ruthless killer who slaughtered five women in the Whitechapel district of London, England in 1888. He was an intimidating and fast talking character, strong willed with a dark sense of humor, who worked as investigative newspaper journalist for Chicago's Independent News Service and going to any lengths to nail down a story. A rival reporter, Jane Plumb, who was also pursuing the story after receiving correspondence from the killer, felt she could arrange a meeting with 'The Ripper' for an exclusive.

Two pilots were made in 1972 and 1973 based on an unpublished novel, called 'The Night Stalker'. The series also included 'They Have Been, They Are, They Will Be', released on TV on September 27th 1974, 'Firefall' released November 8th 1974,  'Horror in the Heights' released December 20th 1974, 'Legacy of Terror' released February 14th 1975, and ended with 'The Sentry' after twenty episodes on March 28th 1975, just eleven days after Donald Lee Bujok's most recent correspondence with the Billings Gazette. The second interesting piece of the article, is the word Donald Lee Bujok used to sign the foot of the letter. He used the word 'Skoal', which is Danish Old Norse meaning cheers or good health, using the same language implied within the SLA letter, stating 'an old Norse word meaning "Kill". On the face of it, these articles to the Billings Gazette appear insignificant, until you bear in mind their close proximity to known Zodiac correspondence and the subject matter involved. This article is courtesy of Kevin Robert Brooks and this is the 'Montana Connection'.