In the world of Zodiac Killer experts, Dave Peterson was the real deal. As a police reporter for the Vallejo Times-Herald in California when the Zodiac began to terrorize the Bay Area with his murders, letters and ciphers in the late 1960s, Peterson covered the case from the start, earning many cover stories and scoops.
He remained deeply intrigued by its mysteries for many decades after, continuing to research leads, analyze evidence and correspond with other experts and aficionados. During his search for the true identity of this elusive serial killer, Peterson amassed a personal archive of hundreds of clippings, letters and hand-written notes, which are chock-full of musings about possible suspects and the meaning of the killer’s tantalizing ciphers. Now made available to the public for the first time by his estate—exclusively on HISTORY.com—the documents offer a fascinating trove of material from one of history’s most notorious serial killer cases—which remains unsolved to this day.
Use the slide show above to scan our selection of the most interesting documents from Peterson’s Zodiac files. For a closer look at the documents, click the links below:
Arthur Lee Allen—Zodiac Killer Suspect
1 of 30 – Arrest memo for Arthur Lee Allen, a Zodiac killer suspect. Filled with personal identifying information, this document was originally meant to be used only within the criminal justice system.
2 of 30 – Front page of a handwritten note exploring the connections between the possible Zodiac killer, Arthur Lee Allen and the alignment of planets and astrological signs.
3 of 30 – Back page of a handwritten note exploring the connections between the possible Zodiac killer, Arthur Lee Allen and the alignment of planets and astrological signs.
4 of 30 – Police note on “Favorite Zodiac Suspect of San Francisco PD,” Arthur Lee Allen, including a handwritten note indicating that the initials “AA” appeared in a Zodiac cipher.
5 of 30 – Police note on “Favorite Zodiac Suspect of San Francisco PD,” Arthur Lee Allen. Added notes include that Allen was sent to a state hospital for molesting kids, is ambidextrous and keeps bodies of small animals in fridges.
Zodiac Killer’s Ciphers & Astrological Connections
6 of 30 – Probable Source of the Zodiac Killer’s Cipher. This note discusses the connection between the book “A History of Secret Societies” by Arkon Daraul and the Zodiac’s ciphers. The Zodiac used three pairs of matching letters and symbols from the marked list.
7 of 30 – Detailed summary of the Zodiac killer’s letters, including where they were sent from, misspellings, length of words and how he managed to avoid leaving fingerprints.
8 of 30 – Zodiac’s 187 Astrology discusses the Zodiac killer’s murders and their possible astrology connections.
9 of 30 – Letter to Dave Peterson from Henry Ephron dated April 30, 1975, discussing the complexities of the Zodiac’s ciphers. Did he mean to just confuse the public? Was he suggesting suicide?
10 of 30 – Letter to Dave Peterson about the Zodiac killer’s ciphers, page 1. Discusses how the Zodiac purposefully arranged his ciphers to be as frustrating to the solver as possible. Also details words they believed they were able to decipher.
11 of 30 – Letter to Dave Peterson about the Zodiac Killer, page 2. Discusses how the Zodiac purposely arranged his ciphers to be as frustrating to the solver as possible. Also details words they believed they were able to decipher.
12 of 30 – Letter from Dave Peterson about the Zodiac killer and his “moon cultist soul brother,” from June 22, 1977.
13 of 30 – Letter to Captain Martin Lee about the Zodiac’s cryptograms and how they believe it is doubtful the Zodiac included his own name amongst his messages.
Riverside City College and the Murder of Cheri Jo Bates
14 of 30 – Letter from Dave Peterson regarding the murder of Cheri Jo Bates. Discusses the details of the murder scene, attempting to discover clues that could help unlock the killer’s identity.
15 of 30 – Notes on the requiem mass for Cheri Jo Bates, killed in Riverside, California. The service was attended by 350 people.
16 of 30 – Dave Peterson’s appeal to Riverside City College to track down Ross Sullivan, a possible Zodiac killer suspect. Dated December 4, 1978.
17 of 30 – Article from November 14, 1966, about the murder of Cheri Jo Bates in Riverside, California.
Other Newspaper Articles Regarding the Zodiac Killer
18 of 30 – Article in California Magazine about amateur sleuth George Oakes, who dedicated significant time to investigating the Zodiac killer. Pages 1 & 2.
19 of 30 – Article in California Magazine about amateur sleuth George Oakes, who dedicated significant time to investigating the Zodiac killer. Pages 3 & 4.
20 of 30 – Article in California Magazine about amateur sleuth George Oakes, who dedicated significant time to investigating the Zodiac killer. Pages 5 & 6.
21 of 30 – Article in California Magazine about amateur sleuth George Oakes, who dedicated significant time to investigating the Zodiac killer. Pages 7 & 8.
22 of 30 – Article in California Magazine about amateur sleuth George Oakes, who dedicated significant time to investigating the Zodiac killer. Pages 9 & 10.
23 of 30 – Dave Peterson’s article on the Zodiac Killer in the Sunday Vallejo Times-Herald, November 22, 1970. Page 1 of “Did Zodiac Slip from S.F. Police?”
24 of 30 – Dave Peterson’s article on the Zodiac Killer in the Sunday Vallejo Times-Herald, November 22, 1970. Page 2 of “Did Zodiac Slip from S.F. Police?”
25 of 30 – Article from November 16, 1972, about the Santa Barbara sheriff department’s belief that the Zodiac committed the 1963 slayings of a couple at Lompac. Page 1.
26 of 30 – Article from November 16, 1972, about the Santa Barbara sheriff department’s belief that the Zodiac committed the 1963 slayings of a couple at Lompac. Page 2.
27 of 30 – Dave Peterson’s article in the Vallejo Times-Herald, “Killer’s Sole Survivor Speaks,” from August 19, 1969.
28 of 30 – Dave Peterson’s article from November 23, 1976, in the Vallejo Times-Herald. “S.F. Links to Zodiac Under Study,” elaborates on the Zodiac being a possible suspect for the San Francisco slayings of LGBT individuals.
Additional Notes on Zodiac-Related Incidents
29 of 30 – Vallejo Police Department notes on James E. Keene, who claimed to know exactly who the Zodiac killer was.
30 of 30 – Report on Santa Barbara double homicide at Gaviota Beach on Tuesday, June 4, 1963.
