Crime investigations

Many forensic shows such as CSI portray the role of a death investigator as one individual who is responsible for conducting all aspects of a death investigation including the on-scene investigation, the autopsy, and subsequent laboratory testing. Explain why this portrayal is not accurate, supporting your answer with the educational/certification requirements of death investigators versus medical examiners/coroners versus laboratory analysts.  Do you feel there should be standardized requirements for each of these roles across various jurisdictions?  Explain why or why not.