On October 29th 2021, Mike Rodelli stated on the Zodiac Killer message board "The fact remains that in 2007 Keel told me, as he had told Lafferty before me, that there is a 1974 forgery based on DNA and the ONLY 1974 letter that had been tested for the presence of cells during Keel's tenure (as demonstrated by the DNA chart that I believe Keel made in about 2000) was the Exorcist letter. This is not rocket science. Even if it is not the Exorcist letter that Keel was talking about, it IS a candidate as being a forgery whose DNA matches the 1978 letter based on the information in the chart".
In his book, The Hunt For Zodiac, he stated "Now there was DNA proof that whoever had penned the April 1978 letter had also penned one of the 1974 letters. And apparently it was not Zodiac. According to the chart of DNA testing results compiled by SFPD's lab in ca. 2000, the only one of the 1974 letters that had been tested by Keel up to that time was the January Exorcist letter. This was the letter that had a swarm of palm prints on it. This created an interesting dilemma that lends credence to the possibility that this is a forged letter. Zodiac had penned a dozen letters prior to writing the Exorcist letter and had never left even a single palm print on them. So why had he suddenly and carelessly taken off his glove(s) to write this one and leave a virtual montage of his palms all over it. From that standpoint alone, it makes sense that someone else may have written the Exorcist letter, its bizarre content notwithstanding. While it is possible that one of the other three letters was tested for DNA subsequent to the compilation of the DNA summary chart that Keel had assembled, I believe that on balance the most likely candidate for being the 1974 forgery is the Exorcist letter until proven otherwise". Mike Rodelli is almost certainly correct that the 1974 Exorcist letter is overwhelmingly the most likely DNA match for the 1978 letter (because it was the only tested in the DNA chart), but here is the almost certain proof that neither the 1974 Exorcist or April 1978 letter were forgeries.
Take a look at the address style, spacing and handwriting of the Exorcist letter envelope (below), and compare it to the two April 1970 communications (in particular the Dragon Card envelope). These two April 1970 envelopes had not been publicly released by 1974. They were the only confirmed Zodiac communications to use the address style of San Fran (dot) Chronicle prior to January 29th 1974. The January 29th 1974 author (if a hoaxer) could never have produced such similarity, or had knowledge of the address style of the April 1970 communications. But the real Zodiac Killer could have.
In the link above, Mike Rodelli argued that the writing on the SLA envelope is consistent with the Stine envelope, 340 envelope, Bus Bomb envelope and Kathleen Johns envelope, stating "It's hard to look at these envelopes and not see the similarities. And note that the November 8, 1969 envelope contained a piece of Stine's shirt, thus proving its authorship as being from Zodiac. There it is in black and white. So the evidence seems to show that, regardless of the timing and his reason for being in Los Angeles on February 3, 1974 (assuming that the letter was posted from there on that date), it was, in fact, the Zodiac killer who sent the SLA letter, not the SLA itself, which, once again, would not have benefitted from its contents. Nor is there any reason why they would have benefitted from imitating Zodiac's handwriting on the envelope but not attributing the enclosed later to him".
Again, if Mike Rodelli is claiming these envelope comparisons are good proof the SLA letter is genuine, he now cannot with any good conscience claim that the comparisons between the Exorcist envelope and the two April 1970 envelopes are not equally as good. Especially when the April 28th 1970 envelope had never been released into the public domain for the author of the Exorcist envelope to copy (not only the handwriting, but the format of San Fran (dot) Chronicle). This being the case, Mike Rodelli (based on his statements) must now accept that the Exorcist letter and SLA letter are genuine Zodiac correspondence. Therefore, if Alan Keel is correct and the 1978 letter DNA matches one of the 1974 communications, we are left with the Badlands card or Red Phantom letter for Mike Rodelli to choose from. But this is what happens to the SLA envelope when we add the "tails" from the Red Phantom envelope. Bearing in mind the SLA envelope wasn't available for the author of the Red Phantom envelope to copy, the writing is virtually indistinguishable from one another, along with a single comma and address format. If Mike Rodelli finds "It hard to look at the envelopes he suggested and not see the similarities to the SLA envelope", he cannot fail to see the similarity between the SLA envelope and Red Phantom envelope. If he believes that the SLA letter was authored by the Zodiac Killer, he now must accept (using his arguments) that the Red Phantom letter was authored by the Zodiac Killer as well. Fortunately, in his book he does.