Forensic Investigation and Document Examination

Forensic investigators use several methods when examining handwriting and documents that are suspected as being forged. In his book, Invisible Evidence, Bill O’Brien describes the way an investigation is undertaken and how authenticity is proven or disproven. Many cases of document fraud involve insurance and the misappropriation of funds.

How Handwriting is Analyzed
Handwriting analysis is a difficult science as a person’s handwriting varies from sample to sample. In some cases, an expert will be unable to reach a definite conclusion. Handwriting is examined using the following criteria:

The bigger the sample, the easier it is to make a match
Writing style, size and slope
Base line habits
Connections between letters
Construction of letters
It is possible to tell which direction a letter was written from by examining writing under a microscope. This is done by looking at the striation marks made by the ball of a ballpoint pen. There are also computer programmes that assist with assessing whether a signature is genuine or not.

Equipment used in Document Analysis
Forensic investigators have access to several machines that enable them to read a letter where the ink has been washed away, see what lies beneath scribbles and read a letter from indentations left on another sheet of paper:

An Electro Static Detection Apparatus is used to visualize indentations by applying an electrostatic charge to a transparent film. The film is laid across the page in question and once the charge has been applied, black toner is passed across the film and reveals any indentations. This method can also determine if something has been added to a journal or log after the original entry was made
A Video Spectral Comparator is used to analyze inks and see whether they are the same or different. This is done by looking at them under different lighting conditions where some wavelengths of light are blocked. This technique can uncover layers in documents where words have been scribbled out or written over
Thin Layer Chromatography is used to do a more thorough analysis of ink. The ink is mixed with chemicals and deposited onto a silicate plate where its constituents can be measured
Infrared Reflectance is used to show the residue of pencil marks. This can be done clearly even if the writing has been erased. Pencils are made of graphite which is a form of carbon – and this absorbs infrared light well
Fraud has become a sophisticated business and forensic science has kept up with it by introducing machines that can detect forgeries. Fake documents and false signatures can be exposed by modern equipment and changes to documents can be detected. Many people leave a trail of forensic evidence without realizing that they are doing so and are ultimately exposed.

Reference:

O’Brien, Bill, Invisible Evidence, David Bateman Ltd, 2007