The Zodiac Killer finished many of his communications with the running victim total. The Dripping Pen card gave us the months of his attacks and a total of seven victims. The Bus Bomb letter stated "up to the end of Oct I have killed 7 people." The July 31st 1969 San Francisco Chronicle letter warned us of future murders: "If you do not print this cipher by the afternoon of Fry.1st of Aug 69, I will go on a kill ram-Page Fry. night." The Halloween card, is also believed by many, to be a future threat towards Paul Avery as his fourteenth victim.
What if we apply this same model to the Riverside Desktop Poem, where he signs off the poem with "Just wait till next time. rh." The Riverside Desktop Poem was discovered in the December of 1966, but there is every possibility that it could have been written prior to the murder of Cheri Jo Bates on October 30th 1966, and the warning of "Just wait till next time. rh" was referring to the time and place of his next murder. Remember, the author of the Confession letter suggested he was trying to lure Cheri Jo Bates into his vehicle. This may possibly indicate he had planned to murder Cheri Jo Bates later than the believed 10.30 pm, when screams emanated from the alleyway - likely on Halloween Day itself - but something clearly had resulted in the unplanned struggle in the alleyway and her 'premature' murder from the perspective of the killer. Had he achieved his objective in luring the young woman into his vehicle, then the likely prediction of the Riverside Desktop Poem would have come true: "Just wait till next time. riverside, halloween."

Many have speculated the author of the Bates letters signed off two of the communications with the letter Z. However, they have a misshapen upper portion, leading many to believe they could again be two letters, in similar fashion to the Riverside Desktop Poem. Despite being joined, the nearest they resemble are the letters M and L.
Bearing in mind the Riverside Desktop Poem may have been written in the early part of October, before the murder of Cheri Jo Bates, it was considered that the letter "h" possibly represented Halloween, thereby presenting an imminent threat. The Bates letters were mailed on April 30th 1967. An imminent threat in this case, bearing in mind April was drawing to a close, would have been the month of May. This would provide the time and date, but what about the location? Many killers will employ a "buffer zone" to their residence or workplace - a distance they can afford to travel without drawing unwanted attention to their home location. Using the most basic form of geographical profiling, we shall look for a home or work location equidistant from the crime scene of the Cheri Jo Bates murder on Terracina Drive, to an area targeted in the month of May, beginning with the letter L. But first, we will look at the evidence discovered in the alleyway close to body of Cheri Jo Bates.

So, let us look at March Air Force Base. This base is located 14 miles from Terracina Drive and 12 miles from Lakeview, almost equidistant between the two. Did the murderer of Cheri Jo Bates reside at the March Air Force Base and was setting his "buffer zone" around this location? Lakeview is bordered by the Upland Game Hunting Area. "BATES HAD TO DIE THERE WILL BE MORE. MAY LAKEVIEW".
This above interpretation is highly speculative and extremely unlikely, so if anyone can offer another possible answer to the two symbols at the foot of the Bates letters, please do not hesitate to add your comments in the section below.

In 1931, it was adopted into the orthography of Shona for a 'whistled' z, but it was dropped in 1955 due to the lack of the character on typewriters and fonts. Wikipedia.
The image in the middle is the character rotated through 180 degrees, similar to the method Zodiac employed in his '13 Hole' and 'Pines' cards, mailed on October 5th 1970 and March 22nd 1971 respectively. The Image on the immediate left is one of the Bates symbols.
Shona: "According to Shona tradition, the afterlife does not happen in another world like Christian heaven and hell, but as another form of existence in the world here and now. The Shona attitude towards dead ancestors is very similar to that towards living parents and grandparents." link.
THE RIVERSIDE PROPHECY [PART ONE]