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television shows about criminal investigations have been popular for years but few viewers understand the intricacies of an actual crime scene investigation. if an autopsy is required masked forensic pathologists examine the body. the body not the murder weapon, is the most important piece of evidence. exact time of death cannot be known without a witness. a forensic pathologist however, can estimate the time of death with certainty. upon death a human body begins to decompose. it goes through several stages of decomposition. knowing the time of death combined with other evidence, may shed light on the cause of death. often the pathologist has crime scene information from detectives at the time of the autopsy. legally, there are five causes of death: natural homicide, suicide, accident, and undetermined. natural causes of death, such as heart disease, cancer, and stroke account for more than half of the natural deaths in the united states annually. criminal cases usually involve unnatural causes of death, such as homicide, suicide and accident.