The 1974 FBI file below reads; Thirty-nine latent fingerprints, eleven latent palm prints and two latent impressions (fingerprints or palm prints) previously reported in this case remain unidentified. These prints were previously compared with available prints of numerous individuals, but no identifications were effected. Ten additional latent fingerprints were previously identified with elimination prints. Unless comparisons are conducted with the known prints of "Zodiac" it is not possible to determine if any of the previously reported prints are his. It is not possible to determine which finger made most of the previously reported latent fingerprints in this case, therefore, it is not possible to assemble a composite set of prints that could be classified and searched in the main fingerprint file.
Comparable areas of unidentified latent fingerprints previously reported on items from different crime scenes, as well as latent prints on different envelopes and letters, were compared with each other, but no identifications effected.
Comparable areas of unidentified latent fingerprints previously reported on items from different crime scenes, as well as latent prints on different envelopes and letters, were compared with each other, but no identifications effected.
The FBI file made one key statement, noting that "It is not possible to determine which finger made most of the previously reported latent fingerprints in this case". In an unscientific analysis of taking the word "most" as a minimum of 60%, would suggest that approximately 40% of previously reported latent fingerprints in the Zodiac case were able to be matched to a specific finger or digit. This would mean 40% of 39, which is as little as 15 to 16 latent fingerprints that could be allocated a specific digit on the left or right hand. If the word "most" was as high as 70% or 80%, the known digits of latents would drop to 12 and 8 respectively. A figure that would probably fall further if we did not include envelopes in our analysis. This clearly demonstrates the lack of quality fingerprints previously reported in the Zodiac case, by virtue of detail and/or size of each partial fingerprint impression recovered.
In 2024 Jarett Kobek mailed me a newspaper article from the Martinez News-Gazette from February 15th 1980, in which the chief criminalist at the Contra Costa Sheriff's Development in Martinez, Gerald Mitosinka, stated "We still have the fingerprints of Zodiac Killer. We still check them against new prints found at crime sites. One examiner knows each of the Zodiac's prints by heart". Obviously, this would suggest (if true) that they should have identified the ten fingerprint digits of the Zodiac Killer from only the pages of the letters he mailed, not the envelopes and postcards, where acquiring all elimination prints is not practically feasible or reliable.
In 2024 Jarett Kobek mailed me a newspaper article from the Martinez News-Gazette from February 15th 1980, in which the chief criminalist at the Contra Costa Sheriff's Development in Martinez, Gerald Mitosinka, stated "We still have the fingerprints of Zodiac Killer. We still check them against new prints found at crime sites. One examiner knows each of the Zodiac's prints by heart". Obviously, this would suggest (if true) that they should have identified the ten fingerprint digits of the Zodiac Killer from only the pages of the letters he mailed, not the envelopes and postcards, where acquiring all elimination prints is not practically feasible or reliable.
The machine produced pages of a writing pad (preferably the inner pages of a multi-page letter mailed by the Zodiac Killer), in theory, should contain his fingerprints, if law enforcement have correctly eliminated newspaper staff and themselves as the contributor of any found fingerprints. If we interpret the FBI file when it stated "most", that it was not possible to determine 70% of the time which finger made the previously reported latent fingerprints in this case, it would mean that 30% of the time it was possible. But that would only give us 12 fingerprints in which the digit could be established. And it's highly unlikely that 12 found fingerprints would provide us with the 10 separate digits of Zodiac.
Realistically, after eliminating newspaper staff and investigators, one might expect the remaining unidentified fingerprints on the pages of any letter to be from the Zodiac Killer. So how do we square this circle? I think we have to take the above statement of Gerald Mitosinka with a proverbial pinch of salt, because even after elimination prints, we still can't say definitively that the remaining unidentified fingerprints were donated by the Zodiac Killer. They may very well belong to the Bay Area murderer, but stating it as fact does not appear to be supported by the evidence. An assumption would have to be made after elimination.
To determine the specific digit (e.g., index finger, thumb) a partial print came from, there is no universally agreed-upon minimum percentage or number of minutiae points. The ability to make this determination depends on the quality and unique features present in the visible portion of the print. If we have 12 of these prints (digit recognised) that remain unidentified on the communications (inc. envelopes), it could be argued we have less than 12 reasonable fingerprints of the Zodiac Killer. Only the fingerprints found on the pages inside the envelope, not identified through elimination prints, can effectively stay in the game. Dion Walker in his YouTube video entitled "Zodiac killer FBI files serial 232 ~The ALSA3 latent fingerprint sheets" has concluded "based on the information we have, there could be no less than 11, possibly 12 latent prints on file in the FBI Zodiac file that belong to the perpetrator".
This is a probative analysis and may be subject to change.
Realistically, after eliminating newspaper staff and investigators, one might expect the remaining unidentified fingerprints on the pages of any letter to be from the Zodiac Killer. So how do we square this circle? I think we have to take the above statement of Gerald Mitosinka with a proverbial pinch of salt, because even after elimination prints, we still can't say definitively that the remaining unidentified fingerprints were donated by the Zodiac Killer. They may very well belong to the Bay Area murderer, but stating it as fact does not appear to be supported by the evidence. An assumption would have to be made after elimination.
To determine the specific digit (e.g., index finger, thumb) a partial print came from, there is no universally agreed-upon minimum percentage or number of minutiae points. The ability to make this determination depends on the quality and unique features present in the visible portion of the print. If we have 12 of these prints (digit recognised) that remain unidentified on the communications (inc. envelopes), it could be argued we have less than 12 reasonable fingerprints of the Zodiac Killer. Only the fingerprints found on the pages inside the envelope, not identified through elimination prints, can effectively stay in the game. Dion Walker in his YouTube video entitled "Zodiac killer FBI files serial 232 ~The ALSA3 latent fingerprint sheets" has concluded "based on the information we have, there could be no less than 11, possibly 12 latent prints on file in the FBI Zodiac file that belong to the perpetrator".
This is a probative analysis and may be subject to change.
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