The Questioned Documents unit is responsible for determining the authenticity and/or authorship of documents. The examination can be a handwriting comparison; detection of alterations, obliterations, or indented writing; or discovery of the typewriter, printer, or fax machine that generated a document.

The most common examination is comparison of handwriting or handprinting. Authorship of any type of document may come into question during an investigation:

Everyone has similarities in their handwriting; otherwise we wouldn't be able to read what each other writes. Although the following documents have a great deal of pictorial similarity, they were written by different people:

The forensic document examiner trains for 2 to 4 years in the study of handwriting and other document-related problems. It is the expert's responsibility to examine every element of a writing, including the minute details, and to look for both similarities and differences between known and questioned writing. Notice the similarities between the 2 documents below:

Given enough writing evidence, both known and questioned, the forensic document examiner may be able to identify or eliminate a suspected writer of having prepared a questioned document. The examiner is often called to testify in court and present exhibits to demonstrate the opinion.