When processing crime scenes it is important to evaluate documents that may aid in determining the sequence of events and/or perpetrator of the crime. Such documentation includes, but is not limited to, apparent confessions of a crime or suicide, threatening notes or any other information pertinent to the crime. More generally, the crime scene team will look for handwriting, typewriting, carbon paper, writing or text with alterations, indented writing, photocopies, facsimile machines, notepads, ledgers, checkbooks, diaries, shredded paper, etc.
As with most other forensic analysis, questioned document examination is generally a comparative examination. Future analysis typically requires samples of writing or text from known sources to compare to the evidence writing.
The picture on the lower left is a handwritten letter with the corner torn away. The lower right picture depicts the result of the analysis done on the indented writing from page behind the missing corner of the handwritten letter.
The left side of the picture below is the ESDA film of indented writing from a notebook that the letter on the right was written from.