What is the main reason documents can be considered an important part of crime scene investigations?

Documents play a crucial role in crime scene investigations primarily because they can offer significant insights into the perpetrator's intent. Written materials, such as letters, notes, or digital documents, can reveal the thoughts, plans, and motives behind a crime. For instance, a threatening letter may indicate premeditation, while a diary entry could provide psychological insight into the perpetrator's mindset. Consequently, analyzing these documents helps investigators piece together the narrative of the crime, understand potential motives, and identify suspects.

The other options are less relevant; for example, while authentication of documents can be important, it is often challenging rather than always easy. The notion of entertainment value is not applicable in the serious context of criminal investigations, and the statement about documents rarely changing over time overlooks instances where alterations or forgeries can occur, impacting the investigation's integrity.