Walter Timothy Storey, 47, was executed at 12:01 a.m. Central Time on Wednesday after losing his death row appeal made on the grounds that the lethal drug used for the execution could cause a painful death. The U.S. Supreme Court and the Missouri governor, Jay Nixon, denied appeals to stop the execution. It was the first Missouri execution this year. Storey was given the death penalty for killing a neighbor woman in her apartment 25 years ago in St. Charles, a St. Louis suburb. Storey was pronounced dead at 12:10 a.m., after receiving a lethal injection at the Bonne Terre state prison.

Nixon turned down Storey’s clemency bid at around 8 p.m. Tuesday, shortly after a denial of his appeal by the Supreme Court.  He was sentenced to death three separate times in the same case. Storey was reportedly living with his mother on Feb. 2, 1990, when he became upset over his upcoming divorce. He spent the night drinking and became angry after running out of beer and money, so he decided to break into his neighbor’s apartment to steal money. Jill Frey, 36, had left her sliding glass balcony door open. Storey climbed the balcony and beat Frey in her bedroom, then cut her throat. She died of blood loss and asphyxiation.

Storey cleaned up the apartment the next day, including scrubbing Frey’s fingernails to remove any traces of his skin, but missed cleaning blood off the dresser, leaving a palm print. He was eventually convicted and sentenced to death.

The conviction was thrown out by the Missouri Supreme court due to concerns about ineffective counsel and “egregious errors” committed by the Missouri attorney general’s office. Storey was tried again in 1997 and once again sentenced to death. That conviction was overturned due to a procedural error by the judge. He was sentenced and given the death penalty a third time in 1999.

Missouri’s execution drug, pentobarbital, is obtained from an unidentified compounding pharmacy. Prison officials refuse to disclose details of how it is tested. Storey’s attorney, Jennifer Herndon, argued that this secrecy makes it impossible to know if the barbiturate will work quickly, as intended, or if it will cause an unconstitutionally painful death.

Herndon cited an anesthesiologist who said that the drug could severely disable a prisoner but not kill him, which could possibly leave him alive but permanently brain-damaged. The Missouri attorney general’s office responded that virtually every inmate who has recently faced execution has raised the same issue.

Missouri also uses the sedative midazolam prior to the execution, a drug that was used in three “botched” executions in 2014.