The state of Florida was set Thursday to execute its first death row inmate in nearly two years, and planning to administer a lethal injection cocktail that has never been used before in the United States.
Mark Asay is scheduled to be executed at 6 pm (2200 GMT).
The 53-year-old white inmate was sentenced to death in 1988 for a racially motivated double murder in Jacksonville, Florida a year earlier.
The Florida Supreme Court earlier this month denied Asay a stay of execution. He had challenged the state's plan to employ a lethal injection cocktail that includes etomidate, an anesthetic that has not been used before in US executions.
It will replace another drug, midazolam, which has been the subject of significant legal wrangling.
According to critics, midazolam does not always adequately sedate prisoners, therefore subjecting them to excessive suffering.
In her dissent to the court's ruling Justice Barbara Pariente said the state has treated Asay "as the proverbial guinea pig of its newest lethal injection protocol."
Ashley Cook, a spokeswoman for the Florida Department of Corrections, told AFP the department "follows the law and carries out the sentence of the court."
"This is the department's most solemn duty and the foremost objective of the lethal injection procedure is a humane and dignified process."
Asay would be the first prisoner to be executed in Florida since January 2016, before the state's supreme court ruled that Florida executions were unconstitutional because judges were granted powers that should be reserved for juries.
- Difficult to administer -
Janssen, a pharmaceutical division of the company Johnson & Johnson, developed etomidate and has objected to its use in the lethal injection drug cocktail.
"Janssen discovers and develops medical innovations to save and enhance lives," spokesman Greg Panico told the Washington Post.
"We do not condone the use of our medicines in lethal injections for capital punishment."
Etomidate is difficult to administer and can cause severe irritation and burns if used incorrectly, warned Jonathan Groner, a professor of surgery at Ohio State University who is against the death penalty.
He noted that administering the drug particularly "hurts when it's being injected if the veins are damaged -- and a lot of people on death row have damaged veins because they're either old or they have an IV drug abuse history."
Asay would be the first white man convicted of killing a black man executed in the state since Florida reinstated the death penalty in 1976, according to the Death Penalty Information Center. Since then the state has executed 92 inmates.
Asay fatally shot Robert Lee Booker, an African American, after making racist remarks, according to prosecutors.
He killed his other victim, Robert McDowell, who has been identified as white and Hispanic and was apparently dressed as a woman, after making a deal to pay him for sex.