How Handwriting Analysis Works

Questioned document examiners (QDEs) analyze documents for signs of alteration, forgery and, when sample documents are available, handwriting or typing comparisons to determine or rule out authorship (and/or tie a document to a specific machine in the case of typing).

Handwriting analysis is a tedious and methodical process that relies on extensive knowledge of the way people form letters, including whether they use light pressure or heavy pressure, large letters, narrow spacing and more.

The characteristics of letter formation are unique, and the physiological processes behind writing — the ways in which a person's fine-motor skills can affect his or her handwriting — can leave clues about the author's identity.

Foundations in Childhood

The primary basis of handwriting analysis as a science is that every person in the world has a unique way of writing. When we were all kids in primary school, we learned to write based on a particular copybook — a style of writing. Which copybook our handwriting comes from depends on when and where we grew up.

So at first, we all probably wrote in a similar way to kids of our own age and location. But with the passing of time, those writing characteristics we learned in school — our style characteristics — became only the underlying method of our handwriting. We developed individual characteristics that are unique to us and distinguish our handwriting from someone else's.

Most of us don't write the way we did in first or second grade. And while two or more people may share a couple of individual characteristics, the chance of those people sharing 20 or 30 individual characteristics is so unlikely that many handwriting analysts would say it's impossible.

Style vs. Individual Characteristics

First and foremost, handwriting analysts must be able to accurately distinguish between style characteristics and individual characteristics, which takes a lot of training.

They can pretty much ignore the style characteristics, which are only useful for determining with a fair degree of certainty which copybook the writer learned from. The individual characteristics are what matter the most in determining authorship.­

So the process of handwriting analysis when comparing two documents — one by a known au­thor, one by an unknown author — starts not with checking for similarities, which any of us could do with a fair degree of accuracy, but instead with checking for differences. It's the differences that initially determine if it's possible that the same person wrote both pieces of text.

If there are key differences in enough individual characteristics and those differences do not appear to be the result of simulation (an attempt to disguise one's handwriting or copy someone else's), then the two documents were not written by the same person.

Simulation has its own telltale characteristics. However, if the differences don't rule out a match and there are significant similarities in the individual traits in the two documents, singular authorship becomes a possibility.

Moving from possibility to probability is where the heavy lifting comes in.

Analyzing handwriting is a long, careful process that takes time and, under ideal circumstances, a lot of comparison samples, or exemplars — documents that have a known author. It's not a matter of looking at two documents and saying, "Hey, they both have a 'B' with a downstroke extending below the line — same author!"

In the case of the Lindbergh kidnapping in 1932, the police had a slew of questioned documents — in all, the kidnapper sent 14 notes to Lindbergh with ransom instructions. Handwriting analysts had no problem determining that the same person wrote all of the ransom notes.

But pre-existing exemplars from the main suspect, Richard Bruno Hauptmann, were scarce, so the police had to get samples from Hauptmann in the police station by way of dictation. From those requested exemplars, handwriting analysts determined a match.

­However, the police officers' methods of obtaining those samples have since been called into question — they forced Hauptmann to write for hours and hours until he nearly passed out from exhaustion. They also told him how to write, and he was shown a ransom note and told to copy the handwriting as best he could, to name just a few of the major no-nos.

This, of course, means that the validity of the determined handwriting match is in question, and Hauptmann's execution makes a retest impossible. There are now strict rules in place about how police should obtain a requested exemplar.

Good, untainted, numerous exemplars make handwriting analysis far more reliable than a simple one-to-one comparison. While every person's handwriting is unique, no one person writes exactly the same way twice. There are natural variations in a person's writing within a single document.

Having, say, 10 questioned documents and 10 exemplars from a suspect assures that not only will the words and letters in the questioned documents show up in the exemplars but also that almost all of that suspect's individual characteristics will appear in both sets of samples if the suspect is indeed the author of both.

The process of professional, forensic handwriting analysis is all about thoroughness. An analyst will use a magnifying glass and sometimes even a microscope in the comparison process. When looking at writing samples, an analyst is looking for a wide array of individual traits:

With these traits in mind, we'll take a look at one common method of comparison in which the analyst begins with the first letter in the first word in the questioned document and starts building a table.

To illustrate the process, we'll perform a simulated comparison using a questioned document and an exemplar each consisting of a single sentence — a nightmare for determining a definite match or non-match in the real world, but perfect for our purposes.

At first glance, the two samples do not appear to be different enough to automatically declare that two different people wrote them. And on closer examination, they actually appear to be quite similar. So we're going to build a table that catalogs each varied form of every letter that appears in the questioned version of this sentence.

If we get to an "a" that looks exactly like an "a" we already have in our table, we skip it. We simply want each different formation of "a" in the document in our table, taking into consideration letter formation, linking strokes, spacing and other traits.

In forensics, they would "copy" each letter form using a digital camera, but we're going to do it by hand. They would also make separate tables for uppercase and lowercase letters. But we're going to simplify since this is only an example of the process of determining a match or a mismatch and not a professional or accurate comparison.

Next, we're going to make the same kind of table using the exemplar.

Finally, we're going to compare the tables and see if we have a match for each questioned-document letter form in the exemplar. Since our document consists of a single sentence, we don't have many instances to choose from.

Under normal circumstances, we would have an array of potential matches for each letter form, and we'd want to find a good match in the exemplar for every letter form occurring in the questioned document.

For simplification purposes, our third table is going to consist of a side-by-side comparison of our two initial tables, although an expert analyst would probably create a third table showing the exact words in each document that make up each letter-form match.

While this analysis would definitely not hold up in court due to its extremely limited scope (and sadly inaccurate letter copying), it nonetheless seems we have found a match in the exemplar for each letter in the questioned document. The same person probably wrote both sentences.

But what if the writer of the exemplar was trying to copy the handwriting in the questioned document? The problem of simulation is a difficult one in handwriting analysis. Simulation occurs when a person is either trying to disguise his handwriting to prevent the determination of a match or to copy someone else's handwriting to encourage the inaccurate determination of a match.

While simulation makes an accurate analysis far more difficult (and sometimes impossible), there are certain traits that professional analysts look for to determine whether a handwriting sample is the result of simulation. These include shaky lines, dark and thick starts and finishes for words and a lot of pen lifts, all of which come from carefully, slowly forming letters instead of writing quickly and naturally.

Simulation is just one of the factors that can foil an accurate handwriting analysis.

­While an expert analyst can detect many instances of forgery, a good simulation can be undete­ctable. One example of a forgery the experts missed is the case of the "lost" Hitler diaries. (Although there's a good reason why they missed it.)

In the 1980s, a man named Konrad Kujau, a supposed collector of Nazi memorabilia, approached a German publishing company with 60 handwritten journals that Adolf Hitler purportedly wrote that had, according to Kujau, just been discovered in the wreckage of an airplane that had left Germany after World War II. The texts seemed to be genuine, and Kujau had an apparently good reputation, so the publishing company paid $2.3 million for the lot.

Initial Confirmation

The company immediately published the diaries in installment form in a German newspaper owned by the same publishing company, and they sold the syndication rights to several international publications, including The London Times. It was The Times that requested a professional handwriting analysis to ensure authenticity.

Three international experts in forensic handwriting analysis compared the diaries to exemplars that Hitler apparently wrote. All agreed that the same person who wrote the exemplars wrote the diaries. The diaries were for real.

Material Differences

It was an analysis of the ink and paper used to write the diaries that revealed them as fakes. An ultraviolet-light examination revealed that the paper contained an ingredient that wasn't used in paper until 1954. Hitler died in 1945.

Further forensic tests on the ink showed it had been applied to the paper within the last 12 months.

A Second Twist

As it turns out, though, the handwriting analysis was in fact correct — the person who'd written the diaries had also written the exemplars. Kujau, later found out to be an experienced con artist, had also forged the exemplars the police were using as comparison documents.

Lessons Learned

The Hitler diaries debacle is an extreme case of fraud and expert forgery that spanned every stage of the analysis. And while this level of expertise is rare in forgeries, the fact remains that if the investigation had relied on handwriting analysis alone, the "lost Hitler diaries" would now be part of the history books.

Some other issues affecting the accuracy of handwriting analysis include:

­In the initial comparison work done in the case of John Mark Karr, who confessed in August 2006 to the 1996 murder of six-year-old JonBenet Ramsey in Colorado, the ransom note found in the Ramsey house was long enough to be useful as one side of the equation, but finding good exemplars was an issue.

In a series of preliminary handwriting analyses, documents expert John Hargett, former head of document analysis at the U.S. Secret Service, compared the ransom note to two exemplars: a yearbook inscription written when Karr was in high school and a job application Karr filled out in Thailand.

Hargett found no matches, although the results were inconclusive because the yearbook inscription was written more than 20 years ago and in an artistic writing style, and Karr filled out the Thailand job application in all uppercase letters, while the ransom note was written in both uppercase and lowercase letters.

DNA testing later made further handwriting comparisons unnecessary, as Karr's DNA was not a match for the DNA found on JonBenet's body.

The Biggest Drawback

Certainly, the most significant shortcoming of using handwriting analysis as a scientific basis is the fact that it is ultimately subjective. This means that its acceptance in the scientific community and as evidence in court has historically been shaky.

Only recently, as the training of analysts has become more standardized and organizations have put certification procedures in place, has handwriting analysis started to gain more acceptance as a reproducible, peer-reviewed scientific process.

The results of a handwriting comparison are still not always accepted as evidence in a court case, partly because the science has a few more hurdles to clear, including determining a reliable error rate in analysis and setting standards for the comparison process.

The addition of computerized handwriting analysis systems to the process, including the FISH (Forensic Information System for Handwriting) system, which allows examiners to scan in handwritten documents and digitize the comparison process, may speed up the process of general acceptance of handwriting analysis as a science and as expert evidence in court.

You might have heard that if your handwriting is really tiny, you're subconsciously trying to hide; or that if you write the initial letters of your first or last name much bigger than the other letters, you like attention.

These types of analyses, which can tell you if you are expressing rebellion or prefer to avoid confrontation by the way you write, are part of an art called graphology, which has nothing to do with the science of forensic handwriting analysis.

Forensic handwriting analysis is about comparing two or more documents and determining within a reasonable degree of certainty that the same person wrote them or that different people wrote them.