This Is the Zodiac Speaking: Who Is Suspect Arthur Leigh Allen and Why Do His Former Students Think He Was the Zodiac Killer?

The Zodiac Killer case remains unsolved, and three former students of a lead suspect are still looking for closure.

In the late 1960s, a serial killer who called himself the Zodiac murdered at least five people in Northern California. He taunted police by sending letters accompanied by ciphers to local news outlets and claimed that he was responsible for more than 30 deaths.

The Zodiac was never caught — and there are countless theories regarding his true identity. However, the late Arthur Leigh Allen, a Navy vet turned school teacher, has remained one of the authorities’ leading suspects for the past 50-plus years.

Now, Netflix’s three-part docuseries titled This Is the Zodiac Speaking, which premiered in October 2024, brings a new perspective to the forefront. The true crime series features interviews with the Seawater family who considered Allen a father figure and now believe him to be the true Zodiac killer.

Here’s everything to know about Arthur Leigh Allen and why the Seawater family thinks their longtime friend may have been behind the infamous killings.

Who was Arthur Leigh Allen? 

Arthur Leigh Allen was a Navy veteran. In the early 1960s, he lived in Atascadero, Calif., where he worked as a teacher at Santa Rosa Elementary School.

According to several of Allen’s former students, he was known for teaching his pupils how to decipher codes and playing music in his classroom, including songs like “Tom Dooley” about the murder of a woman, and “I’ve Got a Little List” from The Mikado — an opera with themes of death and cruelty. Allen also enjoyed collecting animals and bringing them to school. David Seawater specifically recalled a frog that Mr. Allen named “forg” in This Is the Zodiac Speaking.

Investigators have since drawn connections between Allen’s classroom activities and the Zodiac’s infamous communications. One of the Zodiac’s letters specifically quoted lyrics from “I’ve Got a Little List,” and the serial killer was known for purposely misspelling common words.

In 1963, Allen moved to Northern California. Nearly a decade later, he was arrested for molesting children and sentenced to four years at the Atascadero State Hospital. The Zodiac’s killings and letters ceased during that time.

Allen eventually died in his home in 1992 at the age of 58.

Were the Seawater children related to Arthur Leigh Allen? 

The Seawater children were not biologically related to Allen, but they considered him a father figure. “Mr. Allen,” as they called him, befriended their mother, Phyllis Seawater, when the eldest Seawaters — David, Connie and Don — began attending Santa Rosa Elementary School in 1961.

Phyllis had seven kids, whom she shared with Paul Seawater. According to This Is the Zodiac Speaking, Paul was institutionalized at Atascadero State Hospital when David, Connie and Dan were young, leaving the Seawater matriarch to care for the kids on her own

Allen, whom Connie described in This Is the Zodiac Speaking as “great, big, burly, smiley, friendly,” would often have dinner with the family and take the older kids on fun outings to the pool or the beach or for a drive in one of his cars.

“He treated us like royalty, like his own kids. We thought he was just the best,” David added.

Why do the Seawater children think Arthur Leigh Allen was the Zodiac Killer? 

In June 1963, before Allen moved to Northern California, he took David, Connie and Don on an outing. They drove to Tajiguas Beach outside of Santa Barbara, Calif., but Allen told them to stay in the car. When he returned, Connie noticed that his hands were covered in blood. The Seawater siblings later learned this was also the same day as the first Zodiac killing, when Robert Domingos and his fiancé, Linda Edwards, were shot on the same stretch of beach.

Three years later, Allen showed up at the Seawater house on his way to Riverside, Calif., and invited Connie to the racetrack. She jumped at the opportunity and David accompanied her. They spent two nights in Riverside, Oct. 29 and Oct. 30, experiencing gaps in their memory. On the second night of their time in Riverside, Cheri Josephine Bates, a student at Riverside City College, was stabbed to death. Connie and David later came to the conclusion that the blackouts they experienced on that trip were likely due to being drugged by Allen.

The last time David spoke to Allen was shortly before he died in 1992. The eldest Seawater recalled the conversation in This Is the Zodiac Speaking, sharing that Allen admitted to drugging him and Connie in Riverside and molesting his younger sister. David said that Allen also allegedly confessed to being the Zodiac Killer.

Where are the Seawater children today? 

Following his conversation with Allen, David told his mother and siblings what he’d learned, but they didn’t believe him. David and the family were estranged for years until they all saw the 2007 film Zodiac starring Jake Gyllenhaal as reporter Robert Graysmith and John Carroll Lynch as Allen.

“The three of us started piecing together these jigsaw puzzle pieces of our childhood, and a hundred things finally fell into place,” Connie said in This Is the Zodiac Speaking. David added: “We started researching things and realized that we had been to all the murder sites before the murders.”

After the police showed little interest in their findings, David, Connie and Don agreed to participate in the Netflix series in the hopes of giving everyone involved some closure.

“The things we connected the dots with are real. If they can somehow, some way, help solve this case, whether it’s him or not, that would be great,” Connie said.

In 2023, after filming for This Is the Zodiac Speaking had wrapped, David died of cancer. He was 73 years old.