Forensic Handwriting Analysis - Comparing Handwriting Between Two Different Documents

Suppose crime scene investigators (CSI's) find a suicide note at the scene of a homicide. How do they know if the deceased is the person that wrote the note or if the note was written by somebody else?

In this article, I will attempt to explain what forensic handwriting examiners look for when comparing handwriting between one document such as a suicide note to a known document containing the person's handwriting.

When making comparisons between two handwritten documents, a forensic handwriting analyst looks for points of consistency and points of discrepancy between the known handwriting standards and the questioned document. The forensic scientist looks for the following:

• Content--Grammar, punctuation, and diction help steer the analyst toward consistent mistakes, repeated phrases, and other hints that suggest at the author's ethnicity or educational level.


• Overall form--The shape, size, slant, proportion, and the beginning and ending strokes of the letters are an integral part of the author's overall form.


• Format and margins--The width of the margins, consistency of the spaces between words, and the slant between lines fall into this group, which encompasses the overall form and layout of the handwriting.


• Line features--Speed of writing, fluidity, and pressure of the pen used give clues about line features as well as the spacing between the letters and words and the connectivity between the letters.

Perspicacious forensic handwriting analysts scrutinize all of these features when making comparisons among documents and signatures. No individual feature makes an accurate comparison, but a combination of features may allow analysts to find out whether suspect and sample writings came from the same person. Based on what they find in their examination, the forensic analyst may conclude that the documents are one of the following:

• Perfectly match


• Mostly match


• Somewhat match


• Do not match at all

Not every analysis yields an answer. The forensic handwriting analyst may also say that he can not come to a conclusion based on the given samples. That particular outcome is not very common. If the handwriting in question is cursive or a signature, a highly trained analyst usually can ascertain whether a certain person created it. If, on the other hand, the questioned document is printed, this job is way too difficult because many of the distinctive characteristics of cursive handwriting are not present in printed material.

To the benefit of law enforcement authorities, many perpetrators are not that smart. This is very evident in written documents, where misspellings are commonplace. Forensic document analysts take advantage of these mistakes. When suspected authors of forged checks or ransom notes are requested to provide handwriting samples for comparison, analysts usually ask them to use the same keyword phrases that were misspelled in the questioned document. If a suspect is the author of a document in question, he or she will misspell the exact same words.

The federal government maintains a database of handwriting samples. The National Fraudulent Check File, Bank Robbery Note File, and the Anonymous Letter File are all operated by the Federal Bureau of Investigation (FBI). These databases contain reference files to which forensic handwriting analysts can compare some questionable documents. There are other high-tech databases that exist such as the Forensic Information System for Handwriting (FISH). The FISH database contains scanned and digitized documents that authorities can make comparisons with. Forensic document analysts visually inspect any consistencies.

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