Document examination expert witness Ronald N. Morris is a certified forensic document examiner and in this excerpt from Submitting a Handwriting Case for Examination, he answers the question:
What is known, sample, or specimen writing?
Regardless of what it is called, this is the known and verifiable writing of an individual that is to be compared to the questioned writing to try and determine whether the writer of the known wrote the questioned writing. Known writing falls into one of the following categories:
a. Requested-Writing by an individual that is specifically written on request for comparison purposes and written while being witnessed. Writing in this category usually consist of material repeating the questioned writing and some containing the same letters and letter combinations while not exactly repeating the questioned writing.
b. Nonrequest or collected-This is writing usually done during the normal course of business, rarely witnessed, and not knowingly prepared for comparison purposes. Its authorship is frequently verified by its writer, and his acknowledgement is believed to be true and/or can be substantiated or confirmed by circumstances surrounding the writing’s preparation. It is important for comparison purposes that most of this writing repeats the questioned material or has the same letters and letter combinations as the questioned writing.
There is no single amount of submitted known writing that is correct in every case. The most important thing to remember is that the submitted writing should be naturally written and representative of the writers writing habits. As a general guideline, if the questioned writing is a signature, it is desirable to have about 30 to 50 sample signatures written around the time of the questioned signature. If the questioned writing is an extended writing such as a letter or note, it is desirable to have all of the questioned writing repeated at least 10 to 20 times. Special handwriting specimen forms and assistance in determining whether sufficient known writing is being submitted are available. Please contact the forensic document examiner (FDE).