Suppose crime scene investigators (CSI) find a suicide note at the scene of a homicide. How do you know if the deceased is the person who wrote the note or if the note was written by someone else?

In this article, I’ll try to explain what forensic handwriting examiners look for when they compare the handwriting between a document, such as a suicide note, to a known document that contains 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 known handwriting standards and the questioned document. The forensic scientist looks for the following:

• happy– Grammar, punctuation, and diction help guide the analyst toward consistent errors, repeated sentences, and other clues that suggest the author’s ethnic origin or educational level.
• General form–The shape, size, slant, proportion, and initial and final strokes of the letters are an integral part of the author’s overall form.
• Format and margins– The width of the margins, the coherence of the spaces between words and the slant between lines are included in this group, which covers the general shape and design of the handwriting.
• Characteristics of the line– The writing speed, fluency and pressure of the pen used give clues about the characteristics of the lines, as well as the space between letters and words and the connectivity between letters.

Shrewd handwriting forensic analysts examine all of these characteristics when making comparisons between documents and signatures. No single characteristic makes an accurate comparison, but a combination of characteristics can allow analysts to find out whether suspect and sample writings come 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:

• Perfect match
• They mostly coincide
• Something split
• They don’t match at all

Not all analyzes give an answer. The forensic handwriting analyst may also say that he cannot reach a conclusion based on the samples given. That particular result is not very common. If the letter in question is cursive or a firm, a highly trained analyst can usually determine if a certain person created it. If, on the other hand, the questioned document is printed, this job is too difficult because many of the distinctive features of cursive writing are not present in the printed material.

To the benefit of law enforcement authorities, many perpetrators are not that smart. This is very evident in written documents, where spelling errors are common. Forensic document analysts take advantage of these errors. When suspected authors of counterfeit checks or ransom notes are asked to provide handwriting samples for comparison, analysts generally ask them to use the same keyword phrases that were misspelled in the challenged document. If a suspect it is the author of a document in question will misspell the exact same words.

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