A medical examiner is a person trained in medicine or a medical organization that investigates deaths and injuries that occur under unusual or suspicious circumstances, to perform post-mortem examinations, and in some jurisdictions to initiate inquests. While many types of medical doctors are capable of performing autopsies, most state or local government laws mandate that an appointed forensic pathologist do the work. These appointees are called medical examiners and have an official position in the county medical examiner system.

Not all counties use the medical examiner system. Some counties use coroners and a coroner's system. There are two major differences between medical examiners and coroners and their corresponding systems. Coroners can be elected or appointed. Some are also sheriffs or funeral home directors. But many coroners aren't doctors. There are also medical examiners, who usually are medical doctors but may not be forensic pathologists trained in death investigation.