(CNN) Eighteen years ago, Kenneth Williams escaped from an Arkansas prison and killed Cecil Boren at his home just a couple miles away.

Williams was scheduled to be executed at the same prison Thursday night -- and Boren's widow, who still lives down the road, is ready for it to be over.

But Gov. Asa Hutchinson put a temporary hold on the execution while the US Supreme Court weighs in on current motions.

If Williams' final court appeals fail, he would be the fourth Arkansas prisoner to be executed in eight days -- a compressed timeline precipitated by a scarcity of fresh lethal-injection drugs as states struggle with suppliers that don't want their products used in executions

Williams' execution had been scheduled for 8 p.m. ET at Cummins prison, the same facility that Williams escaped as an already convicted murderer in October 1999 before killing Boren in nearby Varner.

Earlier, Boren's widow, Gail, had said she plans to witness the execution.

"We just live 2 miles from the prison. ... Every time I go up and down the highway, I know he's there," Gail Boren told CNN affiliate KATV

"We are looking forward to this happening so we can put it behind us."

Last scheduled execution before drugs expire

Williams is one of eight inmates that Arkansas initially wanted to execute in an 11-day span in April, before its supply of sedatives used in lethal injection expires at month's end.

The executions would have been the most in the shortest amount of time since capital punishment returned to the United States in the 1970s. But courts issued injunctions staying four of those executions for various reasons relating to the individual cases.

Because of the delays, and because Arkansas' sedatives will expire at the end of the month, those four inmates will not be executed in April, a spokesman for Hutchinson said.

The crimes

Williams, 38, initially was sentenced to life in prison for the 1998 killing of Dominique Hurd, a University of Arkansas at Pine Bluff cheerleader. But a month after his sentence, he escaped from the Cummins prison in October 1999.

Authorities said Williams went to Boren's home nearby, confiscated his guns and shot him before taking off with his vehicle. Police say he drove to Missouri, where he wrecked with another vehicle as a police officer chased him. The wreck killed the other driver, Michael Greenwood of Missouri.

Williams was convicted of Boren's death and sentenced to execution in 2000.

One victim's family supports clemency, helps Williams meet granddaughter

While Boren's widow plans to attend the execution, the family of another victim is pressing for clemency, Williams' attorneys said Thursday.

The family of Greenwood, the driver who was killed in the Missouri crash, want Thursday's execution postponed so that they can tell the state's parole board that they want him to be spared, Williams' attorneys said.

The parole board, which can recommend to the governor that a condemned prisoner be spared, earlier this year declined to recommend clemency. But the board didn't hear from Greenwood's family, Williams' attorneys said.

On Thursday, Hutchinson responded to the clemency request. In a statement, Hutchinson said he reviewed a letter from the Greenwood family and appreciated "the genuine spirit of forgiveness and compassion demonstrated by Ms. Greenwood."

"Her letter certainly has an impact, however my responsibility is to look at the totality of the case including the view of all the victims and the interest of justice. Kenneth Williams murdered multiple people, and actions have consequences," the governor's statement said.

Earlier this week, Greenwood's family paid for Williams' daughter and granddaughter to fly to Arkansas so they could say goodbye to him in prison. Wednesday's visit was the first time Williams had seen his daughter in 18 years, and the first time he'd ever seen his 3-year-old granddaughter in person, CNN affiliate KARK reported

The daughter, Jasmine Johnson, told KARK about their visit.

"He said tomorrow, no matter what happens, he will at least be more at peace now knowing that he was able to see me and my daughter, as well as everything the Greenwood family has done for him," Johnson told KARK.

Various courts have turned down numerous appeals from his attorneys, including those claiming he is intellectually disabled and thus ineligible for execution. The attorneys filed at least one more appeal Thursday in district court claiming that his medical conditions -- like sickle cell trait and lupus -- put him at risk for severe suffering during the execution. But that complaint was denied and dismissed Thursday evening.

Williams claims he's reformed

Williams, in letters sent to Arkansas journalist Deborah Robinson, says he's become a Christian in prison, and is sorry for killing. Excerpts of the letters were published in essay form this month by Vice and The Marshall Project , a nonprofit news organization that covers the US criminal justice system.

"To the families of my victims, to whom I have brought pain, great loss, and suffering, as shallow as 'I am sorry for robbing you of your loved one' can sound, I would rather say it, and mean it, than not say it at all," Williams writes.

He also wrote that he asked for clemency to he could show the parole board "I was no longer the person I once was."

"God has transformed me, and even the worst of us can be reformed and renewed," Williams wrote.

The arguments over drugs

Williams and the other seven death row inmates initially fought their executions on the grounds that the sedative Arkansas is using -- midazolam, the drug used to render inmates unconscious in botched executions in other states -- does not reliably prevent a painful death. The Arkansas Supreme Court denied the claim.

JUST WATCHED Court rules on the use of lethal injection drug Replay More Videos ... MUST WATCH Court rules on the use of lethal injection drug 01:50

States generally didn't use midazolam in the past, but they've turned to it as drugmakers clamped down on the use of other drugs in executions.

Lethal injection traditionally required a three-drug cocktail: The first (sodium thiopental or pentobarbital) put the prisoner to sleep; the second (pancuronium bromide) brought on paralysis; and the final agent (potassium chloride) stopped the heart.

But manufacturers and European countries started withholding sodium thiopental and pentobarbital this decade, saying they didn't want them used in executions. Arkansas and other states turned to midazolam as an alternative to the anesthetic.

It's unclear when -- or whether -- Arkansas will receive fresh supplies of midazolam after their current batch expires. One manufacturer, West-Ward Pharmaceuticals, filed a brief in support of the eight inmates this month, saying it tries to ensure its midazolam isn't used in executions.