The Z340 (November 8th 1969) was a response to the October 22nd 1969 Jim Dunbar Show, stating that the person who phoned into the show was effectively an imposter or phony, encoding a contemporary message and using wording similar to the headlines in the San Francisco Chronicle on October 24th 1969. The 340 message read, in part "That wasn't me on the TV Show", mimicking the headlines of "That Wasn't Zodiac, Say 3 Who Know" and "It Wasn't Zodiac, Say 3 Who Know". He also responded to the Jim Dunbar Show and the October 23rd 1969 Chronicle article, entitled "A TV Runaround With Zodiac Calls", in which "Belli told Sam he'd attempt to get a promise from District Attorney John J. Ferdon that Zodiac would be spared the gas chamber if convicted of murder". The Zodiac Killer responded in code that he was "not afraid of the gas chamber".
 The Zodiac Killer mailed the Z13 on April 20th 1970, very likely a response to the October 22nd 1969 article in the San Francisco Examiner, entitled "Cipher Expert Dares Zodiac to Tell Name". It read "Dr Marsh told the Examiner today: The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name-in cipher code-would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code, which will truly and honestly include his name". The Zodiac responded on April 20th 1970 by stating "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is___ " The letters N, A, M and E could be found in the ciphertext of the code.
 The Z38 mailed on December 7th 1969 began with "This is the Zodiac speaking. I just need help", mimicking the caller (Eric Weill) to the Jim Dunbar Show on October 22nd 1969. It is clear that this cry for help was a disingenuous attempt at ridicule from a killer who either listened to the Jim Dunbar Show on October 22nd 1969, or read the subsequent newspaper articles. On October 22nd 1969, the Los Angeles Times reported that "Belli was put on the line, and the voice said "I want help". On October 23rd 1969, the Desert Sun newspaper claimed that Melvin Belli told the caller “All of San Francisco wants to help you. The hand is out, you can feel the hands out.” On the same day of December 7th 1969, we have a man mailing a letter to the San Francisco Chronicle mocking the call to the Jim Dunbar Show by stating "I just need help", followed a few hours later by a call to an Oklahoma radio station by a man doing an awfully good impression of the man who rang the Jim Dunbar Show on October 22nd 1969. This impressionist caller could possibly be the Zodiac Killer mocking the Jim Dunbar Show, just as he had done in the letter earlier that day.
Therefore, we have the Z340 (November 8th 1969), Z38 (December 7th 1969), Z13 (April 20th 1970) and Z148 (probably May 3rd 1971), all relevant to the date of October 22nd 1969. Bearing in mind the Z38 carried the same four and five characters from the beginning and the end of the 340 cipher, along with the observations above, we could expect the Z38 message to be somehow related to these other ciphers. The message may very well lie in the newspaper inches from October 22nd 1969 to December 7th 1969 - and may be related to the Jim Dunbar TV Show yet again.