
Newspaper articles from Paul Avery intensified over the months of October, November and December 1969, with two articles in the San Francisco Chronicle on December 29th 1969 and December 30th 1969, entitled "Urgent Appeal By Belli to Zodiac" and "Belli Sure Zodiac Will Talk To Him" respectively. "On Sunday (December 28th), Belli made an appeal to Zodiac to contact him by writing or telephoning the Chronicle". Melvin Belli stressed that any letter and/or telephone call would be treated with the strictest confidence. Therefore, any letter urgently mailed by the Zodiac Killer at the end of December being released into the newspapers, could have possibly scuppered any meeting with Melvin Belli or further contact with the newspaper. So did we have any Zodiac Killer letters at the end of December, mailed in urgency and withheld from the public?

"During 1969, after he sent a letter to Melvin Belli on Dec 20th, there wasn't any communication from Zodiac until April 20th, 1970. Being in New York, NY for four months, could explain why. That would also eliminate several suspects, we know were still in California during that time. Did he go there to spend Christmas with family, or friends, or was it because he had a job there?".
The following envelope, with two affixed 6c Franklin D. Roosevelt stamps, was sent to me by Sandy, postmarked in the afternoon of December 30th 1969 from New York and addressed to Paul Avery. The use of "Air Mail" may have been the urgent and immediate response to the appeal by Melvin Belli, featured in the San Francisco Chronicle by reporter Paul Avery. An envelope not released into the public domain, which underlined the newspaper reporter's name, just like the Halloween card envelope on October 27th 1970, ten months later.
Thanks to Sandy Betts for supplying the following image and accompanying information.