Policie České republiky – Kriminalistický ústav
6
Podpis – originál nebo padělek?
SIGNATURE - ORIGINAL OR FAKE?
A signature is an identifier that bears very individual characteristics of each individual. The image of the signature is stored in our brain and a person transfers it by hand to paper via the skeletal muscle system. The signature is created on the basis of the so-called dynamic stereotype, which is a set of conditioned reflexes created by the automated and repeated writing of the same expression (signature). That is why a person does not even have to think about writing it. In the course of life, the appearance of the signature may change and evolve, but the individual features remain.
1. LUCIA FORENSIC DI system
Handwriting examination experts in the Institute of Criminalistics examine handwritten texts in order to identify the writer, to establish the authenticity of the signature, or to identify the forger of a false signature. Only the graphic aspect of written expressions are examined; personal characteristics of the writer are not assessed.
Concerning continuous texts, especially in italics, the identification of the writer is based mainly on individual deviation from the scribal standards taught at school. This deviation is unmistakable for each individual.
Most often, a signature is forged on important documents of a commercial or legal nature, dealing, for example, with the transfer of property, sums of money or intellectual property. The experts in the Institute of Criminalistics mainly examine contracts, promissory notes, bills of exchange, cheques, powers of attorney or wills. They use modern instrumentation, such as the LUCIA FORENSIC DI system with the Signature programme, which enables precise measurement of the image (signature) captured by a high-resolution digital camera.
2. Continuous written text examination
Nobody writes their signature the same way twice
The basic premise of handwriting examination is that no person signs exactly the same way twice. If a completely identical signature occurs, it is a technical forgery. It can be detected using superprojection.
3. Signature examination
The examiner analyses the questioned and reference text, maps all the graphometric parameters of the questioned text (e.g. font or signature size, slope, height and width ratios, binding, word spacing, layout of the text within the format, etc.), which are then identified in the reference material. In the next stage, the expert analyses the construction and shape of individual letters, components or multicomponents (indivisible combinations of two letters or a letter with a diacritical mark), or the technique of forming numerals, determines the identification value of the characters in the written expression and assesses the quality of their production. When formulating their opinion, the experts apply the elimination method in compliance with the the theory of investigation identification and they exclude impossible or highly improbable hypotheses of the origin of the questioned signature and then decide only between admissible hypotheses.
4. Signature superprojection
5. Examination of continuous written text