Fentanyl, the powerful drug at the center of the nation’s opioid crisis, was used today in the execution of Carey Dean Moore, a 60-year-old inmate at the Nebraska State Penitentiary. Nebraska became the first state in the nation to use Fentanyl in an execution—just three years after state lawmakers voted to ban capital punishment altogether, but were circumvented by Gov. Pete Ricketts.

In recent years, more and more states have had to resort to unorthodox methods of capital punishment as pharmaceutical companies have stopped allowing their drugs to be used for the “cocktail,” as the injection is known. Nebraska itself hasn’t carried out an execution since 1997, and only resorted to fentanyl after exhausting all other options for killing Moore, who was convicted of killing two cab drivers decades ago.

According to The New York Times, two pharmaceutical companies tried to block the execution, saying their reputations would suffer if connected to capital punishment. But prison officials refused to identify which company they purchased the drug for, so the companies’ objections were overruled.

The process of using fentanyl in an execution does raise ethical questions, as there is very little research into how fentanyl affects the human body.

“We really don’t know how fentanyl is going to play out in an execution, as opposed to an opioid overdose,” Deborah Denno, a law professor at Fordham University who has studied capital punishment, told the Times. “Simply because people are dying as a result of fentanyl doesn’t mean they’re dying in a way that would be considered acceptable as a form of execution.”

The execution also comes on the heels of Pope Francis’ bombshell announcement that the Catholic Church now opposes capital punishment in all its forms. This would seem to create a dilemma for Ricketts, a practicing Catholic himself.

“While I respect the pope’s perspective, capital punishment remains the will of the people and the law of the state of Nebraska,” Mr. Ricketts said in a statement. “It is an important tool to protect our corrections officers and public safety. The state continues to carry out the sentences ordered by the court.”