In many parts of the country, the coroner is expected to stand up when the sheriff has gone -- or needs to go -- down.
Throughout American history, sheriffs have doubled as coroners, regardless of medical expertise. This makes sense, as the aims of the sheriff and the coroner are so closely intertwined. This arrangement is not uncommon today in less populated regions, though most counties or municipalities have separated these duties through the use of dedicated coroners or medical examiners.
In many places -- for instance, Peach County, GA -- it's the coroner who assumes the role of sheriff should the sheriff be incapacitated, chiefly because of the law-enforcement nature of the coroner's work and the fact that both are elected positions. Up until the 1970s, the coroner didn't have to wait for the sheriff to be incapacitated; coroners also had the power to arrest and serve as constable. And if it's the sheriff who needs to be served a subpoena, it's the county coroner who often gets the call.
Coroners and medical examiners alike have the power to subpoena medical records and testimony from witnesses.
See the next section for lots more information on coroners and medical examiners.