Forensic paper dating
These samples may come from any number of known sources, such as a particular ink manufacturer or machine.
In cases involving handwriting, samples are usually divided into two types: requested writing specimens and collected writing specimens.
Collected writing specimens, however, are writings that were completed by the subject prior to the investigation.
Good sources of writing specimens may include items such as cancelled checks, letters, diaries, signed receipts, medical records, real estate contracts, tax records or other signed legal documents.
Requested specimens are writings dictated by the investigator to the writer.
(Courtesy of Marie Durina) Determining individual dye components ― An examination called liquid chromatography can be conducted to identify the chemical composition of inks on a document.
In digital documents, evidence could even be culled from the metadata of electronic signature files, providing information such as who the author is and when the document was written.
When conducting examinations, forensic document examiners must have known specimens to which they compare the material in question.
The analysis should be performed by a qualified forensic document examiner, preferably one who is a member of a well-established professional association such as the American Board of Forensic Document Examiners (ABFDE) or the American Society of Questioned Document Examiners (ASQDE).
Membership requirements for these associations vary; however, an examiner typically must have completed a two-year, full-time training program under the guidance of a qualified forensic document examiner.