Questioned Documents
What is the Importance of Indented Writing?

What is the Importance of Indented Writing?

Handwriting is a neuromuscular phenomenon performed by human beings. It is unique and reliable evidence in forensic documentation. Whenever we write something, the handwriting obtained on a surface is the result of the neurological and muscular coordination of the human brain and hand respectively.

The other important factor in handwriting is the pressure applied by the writer on the writing surface through the writing instrument (pen or pencil or any such material).

The pressure applied on the writing surface, especially the paper while writing, results in indentation marks on the paper and subsequent paper sheets placed beneath the writing paper. This is called indented writing, which often manifests itself when pads of paper are used or in some record-keeping situations. It is also called latent handwriting because it is not visible to the naked eye due to the absence of any ink in the writing.

Indented writings are the partially visible depressions on a sheet of paper that were underneath the page on which the visible writing was made while it was being written. The indented writings are helpful in connecting the person with the document. These can be valuable to the examiner by offering significant information, such as phone numbers, names, etc. 

When an anonymous letter is received, it is possible to source the document from indentations. Medical notes and other records can be scrutinized for possible alterations or additions. Impressions found on any anonymous note may provide clues to the identity of the writer, such as the impressions of letters previously written. The development of indented writing may prove that the document has been altered and may not have been made on the date purported. 

A writing addition to a record or file can be revealed by an impression that has been transferred to the page below. Sometimes, indented writing on subsequent pages may not be in agreement with what appears on the surface of the document.

Indented writings found to be out of position, missing, or added after the fact can often be demonstrated by recovering and preserving indented writing from other pages. They can show the sequence in which documents were prepared, the dates at which events were recorded, or proof of the existence of a document that has been destroyed.

Factors Affecting Indented Writing

There are various factors affecting the formation of indented writings. These factors decide the depth and clarity of the indentation writings. Those factors include:

1. Pressure of Writing Stroke

The pressure may vary at different places on the paper. The amount of impressed writing may vary from a whole document or to a few fragments of the letters.

2. Number of Stacked Sheets

The first paper just beneath the originally written paper has the clearest imprint. However, the indentations can be obtained on the second and lower sheets.

3. Nature of Backing Below the Papers

The backing below the papers can be a hard surface or any pliable surface, which affects the formation of indentations.

4. Thickness and Kind of Paper

The material used to make paper and the thickness of the paper are important factors in the formation of indentations. If the paper is thick then the indentations produced on the beneath sheets would be not of much clarity. While the thin paper has more chances of clear indentations. Minute fiber disturbances in the paper also affect the indentation writing.

5. Sharpness and Firmness of Writing Instrument

Sharp pointed writing instruments produce fine indentations. While the blunt writing instruments produce broader indented writings.

Factors Interfering with Formation of Indented Writing

Though indented writings can be deciphered when examined carefully, there are some factors that hinder the clarity of the indentations. They are:

  • Overlapping of the letters on the original writing caused by overwriting on the same page or different pages causing difficulty in deciphering the indentations.
  • Folds and creases of the paper have a severe impact on the indented writings. The folds and wrinkles are usually caused due to excessive handling, which can erase or diminish the clarity of the indentations
  • The visible writing on the original document which may appear as negative or the white image on the transparent film may interfere with the indented writings

Visualization of Indented Writings

In a common process, the indented writing is visualized by rubbing a crayon or pencil, but it is not practiced by forensic examiners as it is a destructive technique. Therefore other methods were invented to do the same.

Photography with oblique light is one such method that is used to visualize indented writings. In this process, the light is placed at an oblique angle which is illuminated on the questioned paper that reveals the furrows of the indented writing.

The shadowed indentations are photographed. Similar procedures are repeated at different angles. Moving the light source and taking multiple exposures fill in most available indentations with shadow, and hopefully reproduce the indented writing. 

It is a useful technique however it is unable to recover the microscopic indentations obtained below 3-4 pages. Another drawback of this method is that it is a lengthy process. However, the results of this method are admissible in court.

The other robust method used in deciphering the indentation writings is the Electrostatic Detection Apparatus or ESDA. It is designed to record the indentations that are obtained below 4-5 pages. The model of ESDA was proposed by Rather Seward in 1998-1999, which is called the charge transport model.

ESDA Detection

The ESDA is a non-destructive method, based on the principle that indented areas of the document carry less negative charge than surrounding areas. This causes the toner used in the Electrostatic Detection Apparatus (ESDA) to be attracted to these areas, revealing indentations that are present on the questioned paper.

It ESDA apparatus is composed of the following:

  • Main Unit (on which document is placed)
  • Imaging film (stretched on the document)
  • Corona Wand (electrostatically charges the document)
  • Toner (black toner powder)

Working of ESDA

  • The document or paper to be analyzed is first humidified as the ESDA works effectively at 60% humidity.
  • A thin film of cellophane or Mylar film is stretched over the document.
  • This document is electrostatically charged using the corona wand (a long thin stick or rod) containing a fine wire charged to 7 kV.
  • When the charge is applied to the paper, then the smooth surface will have a uniform charge. But the indentations produce different charge distributions which result in the formation of a latent image.
  • This latent image is visualized by adding the negatively charged toner (similar to the black toner used in laser printers). This toner electrostatically deposits at the indentations, where the charge congregates. This produces a dark-toned image of the indentations on a grey background. The toner can be applied to the Mylar film by various methods either by cascading tiny glass beads coated with toner over the surface or by puffing an aerosol of toner powder over the surface or by using a device similar to the powder puff to apply the toner
  • The obtained image is made permanent by lamination. Clear sticky-backed plastic is placed over the toner, producing a fixed transparent image. 
  • The permanent ESDA image is removed from the apparatus and kept for further examination. The original document remains unaffected.

The permanent image obtained by the ESDA is dependent on the nature of the document, humidity in the apparatus, the writing instrument used, and the number of paper sheets presented between the original writing paper and the paper placed on the instrument.

Advantages of ESDA

  • It is a non-destructive technique.
  • It is a sensitive technique.
  • It can decipher the indentations up to 7 pages down.
  • It is applicable for documents that are up to sixty years old.

Disadvantages of ESDA

  • Humidity is necessary for the apparatus.
  • If the document is wet, ESDA will get damaged.
  • Indentations on loose papers or glossy papers cannot be deciphered by ESDA
  • ESDA can result in fingerprint development on the document which will interfere with the writing.

Applications of ESDA

The ESDA is useful to examine traced forgery, and questioned documents such as ransom notes or any other important document. All the documents containing indentations can be visualized using ESDA. 


Whenever a person writes something on a paper, there are always changes in the formation of latent impressions of the writing on the papers beneath the originally written papers. These latent impressions are called indented impressions, which are ignored by the individual.

But these indented impressions or writings are of great use from the forensic aspect of questioned document examinations. Therefore, they act as a shred of important evidence in questioned document cases and are admissible in court.

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