United States uses fentanyl for first time in execution of killer

A killer has been executed using the controversial opioid fentanyl for the first time in the United States.

Carey Dean Moore, 60, who had been on death row for 38 years, died by lethal injection in Nebraska.

An unprecedented combination of four drugs, including the first use of fentanyl in an execution, was employed to put him to death.

Fentanyl, a powerful synthetic opioid, is at the centre of the US opioid crisis, which is claiming tens of thousands of lives a year. Prince, the late musician, died after taking fentanyl in 2016.

Fresenius Kabi, a German drug company, tried to block the Nebraska execution by alleging the state had illicitly obtained drugs, but a judge refused to stay it.

The company accused Nebraska of improperly using its drugs. Nebraska argued that one of its execution drugs was set to expire on Aug 31, and that prison officials would not be able to purchase more.

It was the first execution in Nebraska since 1997.

At a glance | Fentanyl

Moore was one of the nation's longest-serving death row inmates.

His execution came three years after Nebraska abolished the death penalty, only to have it reinstated the following year in a referendum when 61 per cent of voters backed capital punishment.

Moore died at the at the Nebraska State Penitentiary in Lincoln.

He had been convicted of the 1979 shooting deaths of two Omaha cab drivers, Maynard Helgeland and Reuel Van Ness Jr.

The unprecedented Nebraska lethal injection cocktail called for an initial IV dose of diazepam, commonly known as Valium, to render the inmate unconscious.

Fentanyl was then administered, followed by cisatracurium besylate to induce paralysis and stop the inmate from breathing, then potassium chloride to stop the heart.

After each injection prison officials sent saline through the IV to flush out any residue and ensure all the drugs have entered the inmate's system.