When one document is written out while resting on another sheet, impressions from the writing on the upper sheet are formed on the lower sheet.
Depending on the pressure used and the writing implement impressions may be found up to 6 sheets below the written sheet.
Examination for indented impressions may be useful in a number of different case types. Anonymous letters can be examined to determine if there are impressions such as a name or telephone number that may indicate their source. Witness Statements or Contracts can be examined to see if there is evidence of previous pages indicating that pages may have been substituted. Notebooks or diaries can be examined to determine the content of pages that have been removed.