The comparison of handwriting and signatures can provide very powerful evidence in a wide variety of case types. If an individual can be shown to have written a piece of writing then this can show intent in a particular case. Forensic handwriting comparison should not be confused with 'graphology' where practitioners purport to determine personality traits from handwriting.
Handwriting comparison requires the meticulous comparison of each and every character and can only be carried out in a like for like fashion (e.g. comparing block capitals with block capitals, numerals with numerals etc.). Additionally each writer demonstrates a range of variation in their handwriting. As a result of these two factors the outcome of any particular comparison is strongly influenced by the quality and quantity of the reference writing provided for comparison. Ideally the reference material will be directly comparable with the questioned material but also demonstrate the range of variation. Usually the best solution to this is to provide dictated specimens on request as well as 'course of business' writings which have been produced in the individual's day to day activities. It is also important to ensure that reference writing was produced at around the same time as the questioned writing, as handwriting can change over time.
Signature comparison is a special case of handwriting comparison. Signatures often evolve into more complex forms than an individual's writing because they are frequently written. Sometimes the characters which once made up the written name in the signature become illegible and the signature becomes a written pattern. Generally speaking, the more complex a signature is the more identifiable it is. Again, it is important to establish the range of variation present in an individual's reference signatures.
Importance of original documentation for comparison work
It is important to obtain the original documents for examination where these are available. It is appreciated that on some occasions this is not possible as the originals may have been destroyed. Opinions can be given based on copy documents but this can reduce the amount of evidence available to the examiner and can therefore degrade the level of opinion. If a copy is the only thing available the investigator should ensure that the 'most original' is obtained. A fax of a copy, for example, will be liable to contain much less evidence than the copy which was faxed as the faxing process further degrades the image.
Our handwriting experts have vast experience of studying many different writings. This is important as features such as national characteristics and disguised handwriting can lead the casual observer to very wrong conclusions.