After more than three decades on death row, a convicted murderer has died on Tennessee's death row.

David Lee McNish, 63, was found unresponsive in his cell at the Riverbend Maximum Security Prison in Nashville, the agency said.

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McNish was sentenced to death for the 1983 murder of an Elizabethon woman in 1983. Investigators said McNish used a glass vase to beat 70-year-old Gladys Smith to death.

McNish had been awaiting execution for 32 years, since he was sentenced in 1984. More inmates died of natural causes on Tennessee's death row between 2004 and 2014 than were executed.

David Miller, who was sentenced to death in 1982, is the longest-serving inmate. He killed a disabled woman with a fire poker in 1981 in Knox County.

There are 64 people on Tennessee's death row, including one woman. Christa Gail Pike was convicted in 1996 of the murder of a fellow Knoxville Job Corps student.

The last person executed in the state of Tennessee was Cecil Johnson, who was convicted of murder in Davidson County. He was given a lethal injection on December 2, 2009. Since then, ten inmates sued the state over its lethal injection protocol, claiming the state's single drug method could cause extreme pain and lingering death.

For more information on Tennessee's death row, click here.