These two letters were authored by the same individual, expressing "I just need help", but neither were published in the newspapers - so when the December 20th 1969 'Melvin Belli' letter arrived just days later with a piece of taxicab driver Paul Stine's shirt and proclaiming "please help me", it goes a long way to authenticating the Fairfield letters as genuine Zodiac correspondence. Rubislaw, a regular contributor to this site, pointed me in the direction of the Spiro Agnew Files in the FBI archives, regarding threats (including bomb threats) made to President Richard Nixon in 1973 (return address Leavenworth, Kansas). Rubislaw pointed to a comparison between these threats (of which there were many) to the Steve McQueen threat letter mailed in 1977 (which included a threat to President Jimmy Carter), and highlighted on the Zodiac Killer Site forum. The comparison is justified, irrespective of whether they were authored by the same individual, as the threats were aimed at high profile people in news and television. But for now I shall concentrate on the Richard Nixon threat and the December 16th 1969 Fairfield letter.
The December 16th 1969 Fairfield letter opened with the line "I just want to tell you this state is in trouble..I will go for the Goverment life". One of the Richard Nixon letters dated May 14th 1973 began "This is just to tell you, that you will die. There is no way to stop it believe me". There is a similarity in wording, which obviously may be coincidental, but both are a threat on "government life", refer to "pigs" or "cops", the two communications are written on lined paper and both have a circle as part of the logo. They are probably two separate individuals, but nevertheless, it cannot be dismissed out of hand that the Zodiac Killer may have gone through an evolution in the intervening three and a half years, developing the gravity of his threats. I certainly understand the drawbacks of handwriting comparisons, but here are the December 16th 1969, May 14th 1973 and June 8th 1977 (Steve McQueen) letters, all written on lined paper - and in which - each contained either "to tell you that", "to tell you this" and "to tell the people".