FBI's Secret 1975 Fingerprint Request in the Zodiac Case

# FBI's Secret 1975 Fingerprint Request in the Zodiac Case

By DeClassX

By the summer of 1975, the Zodiac Killer had not claimed a confirmed victim in over five years. The taunting letters to newspapers had slowed to a trickle. Law enforcement agencies across California had accumulated mountains of tips, suspect files, and forensic evidence — and seemingly very little to show for it. Yet the FBI had not gone quiet. A single declassified teletype, dated August 19, 1975, offers a rare, granular glimpse into how the Bureau was still actively working leads deep into the decade, quietly and confidentially — and, in this case, with the help of military records.

The document is a confidential teletype transmitted at 7:42 PM from the San Francisco FBI field office to the FBI Director in Washington, with copies routed to the Los Angeles, Sacramento, and St. Louis field offices. Its purpose is bureaucratically precise: the San Francisco office is formally requesting that the FBI Laboratory — assigned Latent Case Number A-10042 — conduct a comparison between military fingerprint records on file for a named suspect and latent prints previously developed in the Zodiac investigation. The suspect's name, like much of the substantive detail in the document, has been redacted under exemption b7c, which covers information that could reasonably be expected to constitute an unwarranted invasion of personal privacy in law enforcement records.

What survives the redactions is still revealing. The suspect is described as a White Male American — a WMA in FBI shorthand — whose name has been withheld but whose date of birth and current residence in a California town ending in "Express" are also blacked out. A confidential source within the San Francisco office had flagged this individual with a striking characterization: he was reportedly a "look alike" for the subject designated in Bureau files as LOD IAC. That designation, LOD IAC, refers to the Zodiac case file classification — "Lodi IAC" or variations thereof were internal Bureau shorthands used to categorize the investigation. The phrasing "look alike" is notable, suggesting the tip was at least partly rooted in visual resemblance to composite sketches or descriptions that investigators had been circulating for years.

Beyond physical appearance, the memo hints at a deeper evidentiary rationale for treating this individual seriously. Several lines — now redacted — describe his background, including what appear to be references to military service. The surviving text explicitly states that "his service assignments believed to include duty" at locations now hidden behind black bars. This detail matters enormously in context: one of the enduring investigative threads in the Zodiac case has been the possibility that the killer possessed technical or tactical knowledge consistent with military training. The cipher letters sent to the San Francisco Chronicle and other newspapers, the cryptographic sophistication of the Zodiac's coded messages, and the methodical nature of the attacks all fed speculation about a possible military background. This 1975 teletype suggests that federal investigators were actively pursuing that angle at least seven years after the first confirmed Zodiac murders.

The fingerprint comparison itself — the core request of the memo — speaks to how seriously the Bureau was taking this particular lead. Latent fingerprints had been recovered at Zodiac crime scenes and from correspondence attributed to the killer. Matching those prints to a suspect's military service record, which the U.S. government maintains as a matter of course for all enlisted personnel and officers, would be a definitive forensic step. It would not be circumstantial. If the prints matched, the investigation would have crossed a critical threshold. The fact that the request was routed through official FBI Laboratory channels — rather than handled informally — indicates this was not a casual inquiry. Case number A-10042 and Laboratory reference number D740821019 both appear in the header, suggesting a paper trail that predates this particular teletype by nearly a year.

The routing of the memo to multiple field offices — Los Angeles, Sacramento, and St. Louis — is also worth examining. Sacramento was listed as the "Office of Origin" for the Zodiac investigation within the FBI's internal structure, which explains its inclusion. Los Angeles's presence may reflect prior investigative work or a suspect with ties to Southern California. St. Louis is more intriguing: the National Personnel Records Center, which holds the military service files for millions of veterans, is located in St. Louis. Its appearance on the distribution list strongly implies that the Bureau's request for the suspect's military fingerprint cards — called "WINTS" in the document, a reference to inked fingerprint cards submitted at the time of military induction — was being coordinated through that office.

A stamped notation at the bottom of the page reads "SEP 5 1975," approximately two and a half weeks after the teletype was sent. This is almost certainly a received or processed date, suggesting the laboratory or a routing office acknowledged the request in early September. Whether a fingerprint comparison was actually completed, and what it found, remains unknown from this document alone.

That ambiguity is the document's most haunting quality. The heavy redactions that protect the suspect's identity make it impossible to know whether this individual was ever eliminated, whether the prints matched, or whether the lead simply dissolved into the fog of an unsolved case. The Zodiac investigation was notorious for generating credible-seeming suspects who ultimately could not be definitively linked to the crimes. This memo may represent one more name quietly added to that list — or it may represent something closer to a real answer that was never publicly disclosed.

What this document confirms, without ambiguity, is that the FBI was running serious investigative work on the Zodiac case well into the mid-1970s, leveraging federal resources — including military records — that local California law enforcement could not access as easily. For researchers and investigators still working this case today, that raises a pointed question: what did the FBI Laboratory conclude about Latent Case A-10042, and does that comparison result survive somewhere in the still-classified portions of this archive?