UPDATE: Story updated at 12:22 p.m. with new information about the execution.

Carey Dean Moore, a 60-year-old who has been on Nebraska's death row for nearly four decades, just became the first inmate to be executed with an experimental drug cocktail including fentanyl, the powerful synthetic opioid at the center of an overdose crisis around the country.

The execution, Nebraska's first in more 20 years, was carried out Tuesday shortly after 10 a.m. CT. A witness from the Associated Press said the process took about 15 minutes from the moment of the first injection. The Nebraska Department of Correctional Services said Moore was pronounced dead at 10:47 a.m.

A murderer named Scott Dozier was expected to become the first inmate executed with a course of drugs including fentanyl in Nevada in July, but a judge halted the execution when one of the makers of the sedative midazolam objected to its use as part of an execution.

Moore, who killed two cab drivers in Omaha in 1979, had seven other execution dates scheduled before Tuesday’s, according to NPR. Like Dozier's case, a drugmaker had attempted to block the execution based on allegations that some of the drugs set to be used were obtained illegally, but a federal judge declined that company’s request for a temporary restraining order on Friday.

Dozier, who was convicted of two murders, was previously scheduled to be the first inmate executed with fentanyl. The execution cocktail would’ve also used midazolam and the paralytic, cisatracurium. But Dozier’s execution in Nevada was postponed after a drug manufacturer sued the state’s Department of Corrections and accused the state of acquiring its drug through deception.

The untested drug protocol would’ve given Dozier’s lawyers an angle for appeal, but Dozier dropped that effort. He told VICE News in July ahead of his scheduled execution that he wasn’t afraid to die. “You guys get pharmaceutical grade fentanyl and just bang me up man,” he said. “Use a shit ton.”

The supply of execution drugs has been dwindling ever since manufacturers and distributors of common drugs started balking at supplying U.S. prisons for capital punishment purposes. The backlash has forced some states to halt executions entirely, while others have turned to untested drug protocols.

Nebraska lawmakers opted to add fentanyl to the state’s execution cocktail to carry out the first execution there in more than two decades. A petition circulated by various groups over the past week asking Gov. Pete Ricketts to stop the execution garnered more than 60,000 signatures.

"As Gov. Ricketts has said many times, Nebraska is a pro-life state. Resuming a program like the death penalty — which is so prone to error that one innocent person is released from death row for every nine who are executed — is incompatible with one of our most important shared values - the sanctity of all human life," Matt Maly, operations coordinator for Nebraskans for Alternatives to the Death Penalty, said in a statement.

In Moore’s case, Fresenius Kabi, a German pharmaceutical company, sued the state and the Nebraska Department of Correctional Services director over allegations that they'd obtained the drugs to stop Moore’s heart illegally. And although the company said it’s not taking sides on the death penalty, its executives worried that a botched execution resulting from improperly stored drugs could seriously harm the drugmaker’s reputation.

The drugmaker’s complaint, however, was rejected in a federal court on Friday. Another drugmaker’s complaint won’t be addressed in time to delay the execution, according to the Lincoln Journal-Star.

Moore was executed using a combination of diazepam, fentanyl, and cisatracurium. And like Dozier, he hasn’t fought his execution. The American Civil Liberties Union has asked the state’s Supreme Court to delay the execution until the courts rule on a lawsuit filed on behalf of eight death row inmates, although the lawsuit doesn’t include Moore as a plaintiff but as an “indispensable party defendant.”