The Victim Count Assumption

 

For decades, the line “Des July Aug Sept Oct = 7” has been treated as one of the Zodiac’s clearest self‑reported victim totals. The logic behind this interpretation seems straightforward: the line appears just after his last confirmed murder and follows a series of writings filled with self‑applied labels like murderer and killer, references to threats, and descriptions of actual killings. By the time he writes it, the Zodiac has murdered five people, and those murders occurred in four of the five months he lists. To many readers, the months appear to map neatly onto the timeline of his known attacks.

Under this view, the Zodiac is understood to be saying with the code that by the end of October he had claimed seven victims - the five confirmed victims shown above plus two additional, unidentified ones in August. The logic feels intuitive: a killer referencing months and a number that must be tallying bodies. This reading has become so widely accepted that it is often repeated as fact.

But this interpretation rests on assumptions that have never been critically examined. It assumes the Zodiac was using the months as a murder calendar. It assumes he was confessing to two additional killings. And it assumes that the “7” is a victim total. These assumptions have shaped the narrative for more than fifty years, even though the line “Des July Aug Sept Oct = 7” does not explicitly mention victims at all.

In fact, the Zodiac never explicitly states in any previous communication that the number refers to victims, nor does the structure of the line itself resemble a confession. Instead, it reads like a labeled equation or summary heading - something meant to categorize information rather than reveal a body count. The months listed also do not align cleanly with the known murder timeline. The Zodiac did not kill in each of the months he names, and we know this because he has never minded killing in public places and leaving the bodies to be found. If the line were intended as a chronological murder ledger, it is an oddly inconsistent one.

We also know the Zodiac to be a pretty deceptive guy, and he seems to be quite skilled in manipulation. He no doubt would like for people to think that the code was about victims. First, it builds his persona as this powerful and allusive killer. Secondly, it keeps people focused on two additional victims that may not actually exist.

Taken together, these inconsistencies weaken the traditional interpretation. The line may not be a victim count at all, but something else entirely.

Interestingly, the months listed in the line “Des July Aug Sept Oct = 7” correspond more closely to the communications associated with the Zodiac case than to the murders themselves. When the letters and spoken accounts are arranged chronologically, a pattern emerges: each month he names is represented by a communication, even if no letter was written in that month.

December appears at first to be missing, but it isn’t. The July 31 letters describe the December murders in detail, and the August 4 letter revisits them again. July is also covered in both the July and August letters. September has no Zodiac letter, yet it does have a communication - the story the Zodiac told during the Lake Berryessa attack on Hartnell and Shepard - which effectively serves as the “September communication.” October is represented by the Paul Stine letter. In other words, unlike the murder to month assumptions, all five months in the sequence are accounted for through only four communications: three written by the Zodiac and one spoken by a surviving victim.

Once the months are understood as communication markers rather than murder dates, the final piece of the line - the number seven - no longer fits the traditional victim‑count interpretation. If the months represent letters and not crime scenes, then the number cannot be referring to victims. And if it is not referring to victims, the question becomes unavoidable: what is the number for?

The purpose of this analysis is not to establish what the "7" represents - a question that warrants a separate analysis - but to question the assumption that it represents victims. Once that assumption is removed, the line "Des July Aug Sept Oct = 7" becomes open to interpretations that have received far less attention than the traditional victim-count theory.