Not only do the ink from a pen and the type of paper provide clues to forensic document analysts about the origin of a questionable document, many different kinds of mechanical devices do also. Copiers, printers, and typewriters many times leave distinctive markings on the typed or copied document. These markings may show that a particular piece of paper has been altered. Such alterations can help forensic document examiners determine exactly which machine created the questioned document.
In this article, I will attempt to explain what forensic document analysts look for when they come across a printed document that is used in the commission of a crime.
If they are not using pen or pencil and paper, perpetrators often use typewriters to write letters of intimidation or ransom notes. The offenders frequently have the false sense of security that committing such an act makes the letter or note untraceable. Nothing could be farther from the truth. Whenever a typewriter is used to create a questionable document, the forensic document analyst tries to:
- Find out the make and model of the typewriter
- Compare the note with a suspect typewriter
Determining the make and model of a typewriter means that the forensic document analyst must have access to a list of typefaces used in different models of new and old typewriters. Many typewriter manufacturers use either pica or elite typefaces. However, the size, shape, and style of the letter are different, making the analyst’s job difficult. After careful examination of a typed document, the analyst may be able to find out the make and model of the typewriter that created it. Doing so may help shorten the list of exact machines that created the document. On the downside, today’s printers may use daisy-wheel, ink-jet, dot-matrix, or laser printing technologies. These printers vary slightly such that document analysts many times can not discern one from another.
To find out whether a particular typewriting machine created a questionable document, forensic document analysts search for unique characteristics that can involve misaligned or damaged letters, inconsistent spacing before or after certain letters, and inconsistencies in the pressure applied to the page by some letters. For instance, particular letters can have grooves or spurs that are imprinted on a piece of paper. These letters can also slant toward one side or print slightly higher or lower than the rest of the letters on the page. Such abnormalities can be compared to a sample page taken from a suspect typewriter and thus provide powerful individualizing qualities that are unique only to that typewriter.
To make comparisons between a questioned document and a particular typewriter, the forensic document analyst types up a comparison document taken from the suspect typewriter. While doing this, the analyst uses a ribbon that is similar in type and condition to the one used to create the original document. The reason for this is that a worn ribbon will show minor abnormalities in the typeface. On the other hand, a brand new ribbon containing fresh ink may hide them.
Typewriting machines that use ribbons can help the forensic document analyst match a particular typewriter to the document in question. If a typewriting machine uses a single-pass ribbon, forensic scientists can simply read the message from the ribbon itself provided that the ribbon is still in the machine. Even if the ribbon has been used for several passes, criminal investigators can still retrieve parts of the message from the ribbon.
Suppose a crook used the original typewriter to include an extra line or a paragraph to a document? How does the forensic document examiner determine that his occurred? If the typeface is identical in both the original text and the added-on text, it is difficult for the examiner to determine if an alteration occurred. However, when the paper is inserted back into a typewriter for the second time, the alignment many times is off. Taking advantage of this fact, the examiner puts a specially made glass plate with an etched grid pattern on top of the page. By doing so, he can easily view any inconsistencies in the alignment of the added lines and paragraphs.