I think under the circumstances, one is required.
The medical examiner is required by law to investigate and certify all deaths in the District of Columbia that occur by any means of violence (injury), and those that occur without explanation or medical attention, are related to drugs, of persons in custody, or which pose a threat to the public health. Deaths resulting from injuries or complications from injuries – no matter how long after the injury occurred – are still medical examiner cases and fall under the jurisdiction of the medical examiner.
https://ocme.dc.gov/page/ocme-faqs