There can be many questions about the authenticity of a document, who a sample of handwriting may belong to, or the validity of a suicide note. In all these examples, there exists specialists that are trained to examine every aspect of a document and determine if it is authentic or not. These examiners use several techniques to analyze any evidence in their possession.
- Indented impressions – basically, this is the idea that if someone wrote a note on a pad of paper and ripped the top sheet off, the sheets underneath could be examined to look at the marks that pressed through the first sheet and onto the ones below.
- Alterations, obliterations, erasures, and page substitutions – different types of light, such as infrared or ultraviolet, react differently to types of inks. This can show what has been added or removed from the document in question.
- Individual dye components – a small sample from a document can be cut and tested. It can then be matched to an ink library run by the Secret Service, which has collected all ink types produced since 1920.
- Machine-written documents – different machines print in different ways, and can also use unique inks. Both of these factors can be looked at the determine the type of printer a document came from.
- Seals and Stamps – marks made such as “rubber stamp impressions, embossed seals, watermarks, or other mechanically printed marks” can all be examined for any unique features or clues to where the document came from (“A Simplified Guide”).
- Handwriting Analyzation – with a large enough sample of handwriting from two different people, a comparison can be made. No one writes the same way one hundred percent of the time, so even if someone writes very neatly, a skilled investigator will be able to pick up on differences in the writing, such as hesitation or a mistake that was covered up. The age of the person who wrote the document being examined must also be taken into account, as a sample taken from an eight year old will not look the same as a sample given from that same person a few years later at twelve years old, because their writing style develops as they age.
The results from an examination of documents can sometimes be enough to convict suspects of anything from changing the amount on a check to murder. It is very difficult to fake or change a document and get away with it without suspicion.
Source: “A Simplified Guide to Forensic Document Examination.” Forensic Science Simplified. 2013. Web. 19 March 2016.