Christian campaigners have been reacting to the news that Arkansas executed its first inmate in 12 years on Thursday. 

A protracted legal battle threw into question aspects of the death penalty in the United States, which fell to a quarter-century low in 2016.

Ledell Lee, 51, was pronounced dead at 11:56 pm CDT at the state's death chamber in its Cummins Unit prison, a Department of Corrections spokesman said. Lee did not make a final statement.

Lee was convicted and sentenced to death for beating Debra Reese to death with a tyre iron in 1993. Reese's relatives were at the Cummins Unit and told media Lee deserved to die for a crime that ripped their lives apart.

Lawyers for Lee, who had spent more than 20 years on death row, had filed numerous motions in various courts ahead of the lethal injection that had put the process on hold.

Lee had maintained his innocence for years and was seeking DNA tests his lawyers said could prove his innocence.

He was the first person in a group of what had been eight men Arkansas originally planned to execute in 11 days, the most by any state in such a short period since the US Supreme Court reinstated the death penalty in 1976.

Courts have halted four of those executions.

The cases have drawn huge criticism from campaigners who are seeking to abolish the death penalty. Shane Claiborne, the evangelical activist and speaker, has just published a book about the death penalty and was calling for Christians to contact their representatives to prevent the execution. Addressing Arkansas' Governor and Attorney General on Twitter, he wrote: 'Don't forget @AsaHutchinson @AGRutledge It was Christ who stopped an execution by saying, "Let the one without sin cast the first stone."

Don't forget @AsaHutchinson @AGRutledge
It was Christ who stopped an execution by saying, "Let the one without sin cast the first stone."

— Shane Claiborne (@ShaneClaiborne) April 21, 2017

Activist Sister Helen Prejean tweeted in response to the execution: 'Arkansas has killed Ledell Lee. Pray for his family. Pray for peace for the family of Debra Reese. Pray for an end to all forms of violence.'

Arkansas has killed Ledell Lee. Pray for his family. Pray for peace for the family of Debra Reese. Pray for an end to all forms of violence. — Sister Helen Prejean (@helenprejean) April 21, 2017

The state's plan prompted an unprecedented flurry of legal filings that argued the process should be halted, citing problems with US death chamber protocols and lethal injection drug mixes.

Back-to-back Arkansas executions set for Monday were halted indefinitely.

Lawyers for the eight inmates, including Lee, had argued the state's rush to the death chamber amounted to cruel and unusual punishment, violated the inmates' right to counsel and their right to access the courts and counsel during the execution process.

The US Supreme Court denied the petitions for the group. One of them was a five to four decision in which new Justice Neil Gorsuch sided with the four other conservative justices in denying the motion, while the court's liberals dissented.

Republican Governor Asa Hutchinson set the execution schedule because one of the three drugs used in Arkansas executions, the sedative midazolam, expires at the end of the month.

In a dissenting opinion, Justice Stephen Breyer said he took issue with the state trying to use the drugs before their expiration date.

'In my view, that factor, when considered as a determining factor separating those who live from those who die, is close to random,' he wrote.

One of the drugs in the Arkansas mix, midazolam, had been used in flawed executions in Oklahoma and Arizona, where witnesses said the inmates appeared to twist in pain on death chamber trolleys.

Reports said there were no visible reactions from Lee after the drug mix was administered.

'I pray this lawful execution brings closure for the Reese family,' Attorney General Leslie Rutledge said in a statement.

Attention will now turn to other impending executions in Arkansas. The US Catholic Bishops have issued a strong statement condemning the planned executions. 'This Easter, let us ask the Lord for the grace to infuse our justice with mercy,' it says. 'May those in Arkansas who hold the lives of these individuals on death row in their hands be moved by God's love, which is stronger than death, and abandon the current plans for execution.'

Additional reporting by Reuters.