I'll DO IT TO BECAUSE I DONE IT 21 TIMES. I CAN'T STOP BECAUSE EACH ThAT I KILL MAKES IT WORSE AND I MUST KILL MORE. MAN IS ThE MOST PRIZED GAME. ILL NERVER GIVE MY NAME BECAUSE YOU dONT UNDERSTAND. NEXT TIME I WILL SEND A PATCH OF HUMAN SKIN if their is SOME Left OVER.
"Tis the Zodiac Speacking. Why can't you stop me. I can't stop killing. Stop listening t(o) phonys. If this is not on your front page in a week I will skin 3 little kids and make a suit from the skin".
The wording in the letter "I'll do it to because I done it 21 times" is consistent with a mailing date sometime after the March 13th 1971 'Los Angeles' correspondence from Zodiac, claiming 17+ victims. Using a simple calculation we can estimate how often the Zodiac claimed a victim. From December 20th 1968 to July 26th 1970 Zodiac claimed 13 victims over 584 days. That is one victim every 44.9 days. Therefore, from victim 13 to 21, another 8 victims were claimed (8 X 44.9 = 359 days). Add 359 days to July 26th 1970 and we arrive at July 20th 1971, approximately four months after the 'Los Angeles' letter.
This letter and cipher appears at first glance a dubious Zodiac communication, but as Zodiologists.com point out, how difficult would it be for a hoaxer to mimic the ciphers or crosshairs of Zodiac. The fact the author failed to do this, should be pause for thought. There is also something about this letter that indicates the author had written another 'Zodiac' communication (or the author was the actual Bay Area murderer). The other communication, also mailed to the San Francisco Chronicle on July 13th 1971, mirrored the 148 character cipher and letter in one crucial way - the victim total. The last two widely accepted Zodiac communications were the March 13th 1971 'Los Angeles' letter claiming 17+ victims, and the January 29th 1974 Exorcist letter claiming 37 victims. The author of the above correspondence had 19 victim totals to choose from (18 to 36), yet he chose 21, the exact total mentioned in the July 13th 1971 'Monticello' card, which featured in the San Francisco Police Department DNA report under "suspected Zodiac correspondence". Did the author of the above correspondence just get lucky, in accidentally choosing 21 victims like the 'Monticello' card, or was he the author of both?
The 'Monticello' card was mailed on July 13th 1971 stating:
'Near Monticello Shought Victims 21 ...... In The Woods Dies April'.
By my rudimentary calculations the 148 character cipher and letter should have been mailed on July 20th 1971, only one week after the 'Monticello' card. If somebody can find the exact date of mailing regarding the 148 cipher and letter, or when this correspondence was published in the San Francisco Chronicle, it would be of immense value. The 'Monticello' card, by all accounts, was not published in the newspapers. If this were the case, then the victim total of 21, chosen by two independent authors looks extremely unlikely. If the 'Monticello' card was designated as "suspected Zodiac correspondence" by the San Francisco Police Department, then by extension, the above correspondence should be afforded the same value.
She disappeared on April 13th 1971, so the 'Monticello' card (with break added) could be referring to the possible murder of Denise Kathleen Anderson in the woods during April:
'Near Monticello Shought Victims 21 ...... In The Woods. Dies April'.
The 148 character cipher and letter stating "I'll do it to because I done it 21 times" could very well be confirmation that the victim he sought (possibly Denise Kathleen Anderson) had now been claimed.
What are the chances the 'Monticello' card was also mailed from Fairfield? Denise Kathleen Anderson lived in Sacramento, only 43 miles from Fairfield - but was she the 21st victim of the Zodiac Killer?