Investigators often need to examine or verify the authenticity of a document that could be used as evidence in court or aid in an investigation. Such documents are known as "questioned documents."

Through visual examination or advanced chemical analysis of inks and paper, forensic investigators can determine information relating to a questioned document's authentication, authorship or creation date. Such documents, printed or handwritten, could include checks, criminal confessions, counterfeit money, journal entries, threatening letters or wills.

During the analysis of these documents, investigators must be careful not to destroy the evidence.

From: NIJ