NASHVILLE, Tenn. — Tennessee has not performed an autopsy on the four inmates who chose to die in the electric chair since it resumed executions in 2018. 

Documents provided to The Associated Press show that just one autopsy has been performed over the past 18 months, even though six inmates have been executed altogether. 

That one was on an inmate who died by lethal injection. 

Davidson County Chief Medical Examiner Feng Li says autopsies are typically routine because executions are classified as homicides. Yet there are exceptions, including an inmate's wishes. 

Li says all three of the inmates electrocuted indicated they did not want an autopsy.

RELATED: Filing: Emails raise questions of execution drugs access

RELATED: Electric chair vs. lethal injection: Which is the better way to die?

RELATED: Tennessee officials see 'no issue' with latest electrocution

Nicholas Todd Sutton, 58, is the next inmate scheduled for execution on Feb. 20. 

He was sentenced to death in 1985 for the murder of a fellow inmate at the Morgan County Correctional Facility. The victim, Carl Estep, was stabbed 38 times.

Sutton was already serving a life sentence for killing his grandmother, Dorothy Sutton, when he was 18 years old, and he also has been convicted of killing two men in North Carolina, John Large and Charles Almon, also when he was 18.