No, I truly don’t expect a 100% match but I do suspect there will be some similarity or familiarity in a POI’s handwriting to that of Z’s, though subtle it may be. Having said this, If I had a ‘good’ POI whose hand writing didn’t match I’d still continue the research. I wouldn’t rule a POI out by hand writing alone.

the best theory i’ve heard (and one to which i subscribe) is that even when a person attempts to disguise their handwriting there are small fluctuations and consistencies that can’t really be masked.

I personally believe that most of what we see from Zodiac in his writing is his real, every day writing. I think it’s possible he could hide it a bit via turning the page or slanting his writing, making it messier, etc, but I think what we see is his normal writing, some of the formations, spacing, etc. Candy cane F’s, 3 stroke K’s, connecting is capital T to lower case h like in words such as THe. Spacing between the g & h in words like night,fight, etc…I think these are real habits. I am sure that drugs, mental illness, etc could possibly effect writing too. This is all simply my untrained opinion

Depends on what your POI has other than handwriting to rule him IN. From What I’ve seen with most of the guys, that wouldn’t be very much of anything but coincidences. I think there is maybe one handful of guys that can be shown to positively have even anything incidentally connecting to them to the Zodiac case.

With that said it shouldn’t be any surprise that I feel confident in ruling out POI’s based on handwriting…. but I think the bigger issue to keep in mind is that handwriting is perhaps the biggest lead we have as amateur investigators, because it’s really the only piece of evidence that we have access to and are capable of making a comparison.

Handwriting changes due to aging and Parkinson’s syndrome.
Walton J1.
Author information
Abstract
Wills signed by elderly people are often contested on the grounds the the signature is different from their earlier specimen signatures. Neurological disease, which can affect handwriting, is very common and progressive amongst elderly people. Handwriting change due to old age and neurological disease is poorly understood. To better understand this subject, we carried out a large methodical study based on almost 200 handwriting specimens of Parkinson patients and age-matched controls. Interestingly, our findings indicate that some of the handwriting changes which occur in these populations tend to resemble forgery indicia although upon close inspection they are distinguishable from them. Thus, document examiners are urged to exercise caution in assessing purported forgeries on wills and other documents signed of written during older age or a writer suffering from neurological disease.

As a result of the numerous experiments conducted by the authors herein, a group of disguise features and methods was revealed. Most commonly, the disguisers wrote in a way that drastically changed the pictorial image of their writing. The less conspicuous features were less likely to be disguised. For example, the disguiser’s placement of the writing relative to a pre-printed baseline was, as a disguise strategy, rarely changed.

Additionally, the most effective disguises were those methods by which the disguiser:

Wrote with increased pen pressure throughout.
Did not alter letter forms, but rather wrote with notable tremor or erratic movements in an attempt to completely distort the writing or create an appearance of simulation.
A. Some people are capable of writing in a manner so thoroughly disguised that writer identification is impossible.

B. Rarely disguised features include handwritten numbers, addresses on envelopes of anonymous notes, diacritics, titles (Mr., Mrs., Miss, Dr.), punctuation and line spacing.

C. If not an actual case report, the findings from the experiments in these articles include the fact that the participants were writing in non-equivocal real-life disguise scenarios as encountered in forensic casework.

D. You are cautioned against assuming that any single finding automatically becomes a “law” of handwriting identification.

For what it’s worth, back in ’91 or so, I stumbled across a commercial greeting card with its message printed, to my non-graphologist eyes, EXACTLY like Z’s printing.

To do a nice accurate hand writing analysis you need a sample of the suspects writing already done. Such as a letter, even a short one. You need to see how the suspect really writes. Having someone give you a handwriting sample is not the best method to compare against an anonymous letter for example. Writing can be contrived if one is trying to fool you.

preference would also be to have a sample to test from the same time period, 45 years down the track and lots of things can happen to the person in charge of the pen, especially since writing is a less utilized skill since the computer age. still you will retain some if not most characteristic points and flaws depending on health.