What document might indicate previous medical history relevant to a death investigation?

Medical records are vital in a death investigation because they contain comprehensive details regarding the deceased's previous medical history, including diagnoses, treatments, medications, and any pertinent illness or surgeries. These records can reveal pre-existing conditions that may have contributed to the individual’s cause of death or clarify circumstances surrounding the events leading up to their death.

In contrast, bank statements, property deeds, and personal letters do not provide medical information and are unlikely to influence the understanding of medical conditions or health-related issues pertinent to the investigation of a death. Bank statements might illustrate financial concerns, property deeds relate to real estate ownership, and personal letters may offer insight into personal relationships or emotional states, but none supply the necessary medical context that records do.