Warner commuted Robin Lovitt's sentence to life in prison, Warner's spokesman Kevin Hall said.
Lovitt was set to be executed by injection Wednesday night.
Lovitt, 42, was convicted in 1999 of murdering Clayton Dicks with a pair of scissors during a robbery at an Arlington pool hall. Prosecutors said Dicks caught Lovitt prying open a cash register with the scissors. Police later found the scissors in the woods between the pool hall and the home of Lovitt's cousin.
Lovitt admitted grabbing the cash box, but insisted he saw someone else kill Dicks. Initial DNA tests on the scissors were inconclusive.
Lovitt's lawyers, who include former independent counsel Kenneth Starr, who led the special investigation into President Bill Clinton in the 1990s, argued his life should be spared because a court clerk illegally destroyed the bloody scissors and other evidence, preventing post-conviction DNA testing that they claim could exonerate him.
Tuesday's decision by Warner means that North Carolina death row inmate Kenneth Lee Boyd is now likely to become the 1,000th person executed. He is to be executed this Friday.
Prison officials moved Boyd to the death watch area, a small cell block across the hall from the death chamber, on Tuesday afternoon. He was scheduled to begin contact visits Wednesday afternoon with relatives, officials said.
Boyd was convicted of killing his estranged wife and her father in 1988.
in Ohio when the state put to death John Hicks, who killed his mother-in-law to steal her money so he could buy his VCR back from his dealer. Hicks then returned the next day and suffocated his 5-year-old stepdaughter with duct tape over her mouth and nose, so she couldn't tell police he had been at the mother-in-law's apartment.
Hicks, 49, died by injection at 10:20 a.m. at the Southern Ohio Correctional Facility. He was the fourth person executed in Ohio this year and the 19th since the state resumed executions in 1999.