CSI And Document Examination
Richard Saferstein (Former Chief Forensic Scientist) gives expert video advice on: What does a 'document examiner' examine in CSI?; What clues does a document examiner look for in handwriting evidence?; How is handwriting tested in CSI? and more...
What does a 'document examiner' examine in CSI?
Commonly, the document examiner will look at handwriting - forgeries and things of that nature. But there are other types of documents that come into acquisition. Documents such as typewritten documents - whether it be typed by an old-fashioned typewriter or a modern computer printer. Also, documents are examined for manipulation, erasures, alterations, obliterations. And another area of examination will be inks. Using different pens may be a factor, or dating an ink may be a factor, in the examination of a document.
What clues does a document examiner look for in handwriting evidence?
What's most important in the study of handwriting is the concept that no two individuals write alike. This is a very important concept in forensics, because it adds individuality to the investigation. What we look for are the individual's handwriting style. Variations of slope, speed, pressure, spacing, pen movement, writing skills, finger dexterity, margins, grammar, and things of that nature. All those in combination, will lead to a determination as to whether one, and only one, individual did or did not write this specific document.
How is handwriting tested in CSI?
In examining a document's handwriting, there are two possibilities. Either the police investigators are going to be able to obtain writings of the suspect individual by searching a home or by looking for legal documents and things of that nature. Failing that, the individual may then be asked to provide handwritten documents to police under controlled conditions.
What printing devices can a document examiner study in CSI?
Twenty five to thirty years ago, that would've been an easy answer. I would've said the typewriter. However, for the most part, the old-fashioned typewriter today is extinct. We still have photocopiers, faxes, and computer printers that have typefaces associated with them, and those items are commonly examined by question document examiners.
How can a printer's ink markings be compared in CSI?
What's important to look for are the general, what we call, class characteristics of the typescript; its size, a font style, the type of ink that perhaps was used to make the impression of the type. But ultimately what is critical is the existence of wear and tear patterns, or individuality characteristics that are associated with the type. Break in the type, or slight deformations in the type style that came about as a result of use - it is those individual characteristics that will lead to the ultimate identification of the type of the typing instrument.
How can a document be tested for manipulation in CSI?
Manipulation implies irrations and alterations and obliterations. Normally, various photographic techniques, such as uv photography or infra red photography are employed to extract information from those type of documents. Another interesting approach would be in a device know as the ESDA (electrostatic detection apparatus)which is used to determine or detect the presence of indented writings on documents, and that is another rather sophisticated technique that is used in addition to photography.
What are 'indented writings', and how are they detected in CSI?
What is an indented writing? Let me give you an example. For instance, if somebody writes a word on page 1 of a notebook, a copy or an impression of that writing may exist on page 2 or page 3. The way the writing that is exposed or we call the "indented writing" is to use an instrument known as an ESDA, which stands for an Electrostatic Detection Apparatus. This applies an electrostatic charge to the page thought to to have contained the indented writing, along with a charge sensitive toner. The combination of those steps may result in the development of indented writing.
What are 'charred papers', and how are they studied in CSI?
Charred papers obviously come about as a result of a document coming in contact with extreme heat or a fire. How are they made readable? Well, through photographic techniques using reflected lighting or oblique lighting. That's one approach. Or instrumental approaches that require special photographic techniques, such as the application of ultraviolet light or infrared light.