Solved 340-character cipher

Zodiac, the serial killer who terrorized Northern California in the late 1960s, sent four ciphers to local newspapers. The first cipher was separated into three different parts and each part was sent to Vallejo Times-Herald, the San Francisco Chronicle, and the San Francisco Examiner. The combination of all three parts formed a 408-letter cipher, which was decrypted one week after it was received. Zodiac also sent a 340-letter cipher, mailed on a card on November 8 1969, that was recently solved.

UPDATE: Compilation of news reports about the solution

Articles and information about the 340 cipher

High-resolution scan of the 340-character cipher

As it appeared in the SF Chronicle on Nov 13, 1969 (Credit: Deborah Silva, who posts as Seagull on the Zodiac forums)

• Encyclopedia of observations - A collection of observations about the cipher text
• Comparison of cipher alphabets
• Comparison of character repetition rates
• Comparison of sequence repetition rates
• Levenshtein distance analysis - A look at the occurrences of repeated sequences that are not exact matches.
• Quadrant analysis - Do the n-gram counts improve If we split the cipher text into four quadrants?
• Quadrant analysis Part 2 - An expansion of the previous quadrant analysis experiment. Is it possible to produce quadrant arrangements that increase the number and quality of homophones detected algorithmically?
• Information theory (entropy, randomness, etc)
• FBI analysis from Dan Olson
• Cipher-related excerpts from case documents
• Word frequency analysis