Recovering Indented Writing by ESDA

A document fragment by visible light (left) compared to ESDA developed indentation (right).

One role of a forensic document examination is to search for, locate, and make legible indentations arising from prior writing. Such indentations may have been captured on a pad of paper or even a single page that was underlying an original document. Using a technique known as ESDA (Electrostatic detection apparatus), indented writing can often be developed and visualized. In short, ESDA allows our scientists to transform indentations from writing applied to previously removed pages into visible contrast. This can reveal letters, numbers, words, or characters.  A paper may even capture indentations from multiple pages of overlying paper as they were written. In the example above, a seemingly blank page of paper (left) was developed to highlight indentations, which permitted the overwriting to be identified (right). In this example, we have “developed” indentations arising from the original document into legible writing.

Many factors impact the impressions that are developed and the extent to which they can be read. However, it is possible to recover impressions up to several pages deep. The example above shows a phone number whose impression can be read in each of the five pages that were present under the original writing. As with any scientific approach, the actual result from an application of this method will vary on a case-by-case basis; however, ESDA is non-destructive and it has the capacity to provide probative information that is not otherwise obtainable.

Our ISO 17025 accredited laboratory at Microtrace is equipped to conduct ESDA analysis along with a suite of other analyses relevant to the field of forensic document analysis. We have conducted ESDA analyses on a wide variety of documents. These range from forensic document examinations and notes suspected to contain information about a homicide to cryptocurrency key recovery and documents of historical and cultural interest. If you are looking for an ESDA analysis or are interested in a more wholistic forensic document analysis, such as ink or paper, please contact us.

In addition to conducting laboratory analysis of documents by ESDA, Microtrace is equipped with the microanalytical instrumentation and experience to study paper construction, paper composition, paper coatings, additives such as optical brighteners, dyes, and pigments in paper and inks. We also have experience and success recovering and transcribing obliterated, smeared and otherwise degraded writing, using methods that include alternate light sources (UV, visible, and infrared light) and elemental analysis by SEM/EDS, micro-XRF, and radiography. We have experience examining ink to evaluate line crossing order (line sequence), we have studied and compared ink chemistry from both modern, historical inks, and tattoo inks, and we have identified the cause of failure in failure analyses investigations of printed products on packaging.

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