The documentary features interviews with several of Phyllis Seawater's now-grown children, including David, Don and Connie. “Mr. Allen” was the Seawater children's teacher and their eventual father figure after he became involved with their mother after their father was interned at Atascadero State Hospital for molesting one of his daughters. Yes, this poor family went from being a child molester for the father of the family, he literally became the suspected Zodiac Killer (who, by the way, was also a child molester).

This is the zodiac speaking contains many small details from the Seawaters' youth that point to Allen's Zodiac guilt. The Seawaters say Mr. Allen was an incredible swimmer who owned a black wetsuit similar to the clothing described in the Lake Berryessa murder. Connie even remembers sewing a black hood for him. One of the Seawaters' classmates, Darin Alvord, claims that Mr. Allen enjoyed teaching his students all about alphabetic codes and how to crack them.

More important than these small details, however, is the timeline that the Seawaters present. By the end of the three-part documentary, the Seawaters will have claimed to have been taken by Mr. Allen to every single murder site, including Lake Herman, Blue Rock Springs and Berryessa, before the actual murders. Additionally, the Seawaters claim they were taken by Allen to Riverside, California, to watch a stock car race the day before Cheri Jo Bates was murdered on October 30, 1966. Some investigators believe this was Zodiac's first murder. In Episode 3 of the documentary, David Seawater reports that an old and sickly Allen confessed to him in a phone call that he was Zodiac.

Most of the Seawaters' claims fall into the category of eyewitness testimony, which is one of the least reliable forms of evidence – especially when presented so long after the events. However, the documentaries also provide some interesting corroborating evidence for the Seawaters' reports. The most striking new evidence comes from one of the zodiac's many encrypted letters.

In 1973 the Albany Times Union The New York newspaper received a letter purporting to be from Zodiac, postmarked August 1st. To this day it is unclear whether this is an authentic Zodiac correspondence or an imitation. A new detail makes a difference This is the zodiac speaking however, lends a certain credibility to its truthfulness. Connie Seawater's daughter Tammie Lee Prueter remembers watching the History Channel special in 2017 The hunt for the Zodiac Killerin which producers had a supercomputer decipher the encrypted portion of the Albany letter that would reveal the Zodiac's next victim.

The computer allegedly decoded the victim's name as “Connie Henly,” to which they could find no meaning. However, both Connie Seawater and Tammie Lee Prueter report that Phyllis Seawater's maiden name was Hensley. Arthur Leigh Allen was one of the few people who knew this. Combine that with Zodiac's penchant for deliberate misspellings and the fact that Connie Seawater lived in upstate New York in 1973, and it's admittedly a compelling data point.