In the FX program, The Most Dangerous Animal of All, first aired on March 6, 2020, document examiner Patti Fisher inaccurately critiqued the work I performed in 2012 for the book by the same name.

Ms. Fisher said a document examiner must not cherry pick letters and words when comparing the writing on various documents. She also raised the issue that there was an insufficient number of exemplars (documents known to be written by Earl Van Best, Jr.) to use for comparison with the letters written by the Zodiac killer.

Both statements are correct.

What is incorrect are her assumptions about how I performed the analysis, which I documented in my 2014 book, The End of The Zodiac Mystery.

When presented with the challenge in 2012 to perform this analysis, it was immediately obvious that I had too few known documents written by Earl Van Best, Jr. to make a valid comparison with the numerous Zodiac killer documents. The only handwriting I had that was allegedly written by Mr. Van Best was on the marriage certificate for his 1962 marriage to Judith Chandler.

At first, this presented a conundrum. Many document examiners would have declined to continue, stating they could not offer any insight. In fact, at least one document examiner did decline to accept the case, stating there were an insufficient number of exemplars.

Ms. Fisher assumed this was the way I moved forward with the analysis—using one known writing exemplar, which would have provided insufficient data.

This is not how I conducted my analysis. In 2012, after spreading out all the Zodiac documents chronologically in front of me, it took some time, but a lightbulb went off that arose from out-of-the-box thinking. After careful thought, I devised a valid approach to provide the required insight.

The Zodiac documents contained known writing. The killer had provided these documents to the press and to the police departments, in his twisted, manipulative way, to publicize his killings and to taunt the police’s departments’ inability to track him down.

So, rather than treating the Zodiac killer’s letters as questioned documents, I treated them as the known documents. This enabled me to treat the marriage certificate as the questioned document. This shed a whole new light on the subject, enabling me to perform valid research complying with industry standards.

Forensic investigations often require a carefully-constructed approach using unique, valid paradigms. That’s what makes them intriguing.

The ASTM standards Ms. Fisher references in the documentary additionally state that known documents must be compared to determine whether they were written by the same person. The images on pages 17, 19 and 20 in my book, The End of The Zodiac Mystery, validate that I did this.
As a result of this comparison, I was able to eliminate one document provided to me as known Zodiac writing. It was the document written by Detective David Toschi in 1976 to rekindle public interest in the case to increase his visibility and stature. This was revealed in the subsequent documentary. There was an additional document and envelope from 1990 that was not written by the same person who wrote the legitimate Zodiac letters.

After setting the stage using this reverse procedure that enabled me to perform the analysis, the next step I used in my investigation was to determine which words and letter combinations were common—which ones were used in both the known Zodiac documents and the questioned document, allegedly written by Earl Van Best, Jr.

When examining documents, it is invalid to compare different words or letters from two documents with each other—you can only compare the same words or letters to determine if the same person wrote the document in question.
Pages 98 through 108 and 111 of my book illustrate the comparisons I was able to make. In total, I compared 12 letter and word combinations—not just a few cherry-picked items as claimed by Ms. Fisher in the documentary.

Two examples are:
• The letters est from the word Best on the marriage certificate compared with est from the word west in the Zodiac letters.
• The words San Fran on both the marriage certificate and the Zodiac letters and envelopes.

These are only two examples of many letters and words that are common between the Zodiac letters and the marriage certificate. The book provides my complete analysis.

A single similarity of letter or word formations never offers sufficient evidence of a common author. The referenced pages demonstrate many common attributes I discovered among the writings, such as the formation and spacing of the letters, and the location and length of crossbars on the letter E. Again, these are just a few examples of my complete analysis.

Ms. Fisher indicated in the documentary that I cherry picked a few letters, comparing one Zodiac letter at a time with the same letters from the marriage certificate. This is not a proper analysis and it is not what I did. I compared all the writings in the Zodiac letters with the common words and letters in the marriage certificate.

In short, Ms. Fisher’s comments in the documentary did not address the actual procedure I used. Her failure to realize that I was using the Zodiac letters as the known documents as well as not knowing which words and letters I actually compared, led her to reach an erroneous conclusion regarding the validity of my research.

Unfortunately the film crew did not come back to allow me to respond to these criticisms. Had they returned and permitted me to review Ms. Fisher’s critique, the documentary would have been different.