The execution by lethal injection of a convicted serial killer in Idaho was halted on Wednesday after a medical team was unable to insert an intravenous line.

Thomas Creech, 73, was strapped to a table in the execution chamber for an hour as repeated attempts were made to establish an IV line to deliver the lethal drugs, prison officials and witnesses said.

Idaho Department of Corrections (IDOC) director Josh Tewalt said the execution was called off after the failure of eight attempts to set an IV line in Creech's arms and legs.

"We don't have an idea of timeframes or next steps at this point," Tewalt told reporters at the Idaho Maximum Security Institution south of the capital Boise. "Those are things we will be discussing in the days ahead."

Brenda Rodriguez, a reporter with the local KTVB television station, said Creech did not appear to have been in severe pain at any point although he told the medical staff at one stage that his "legs hurt a bit."

"At the very end, when the execution was halted, he was just looking up," said Rodriguez, one of four media witnesses.

"He kept mumbling a couple of words that I could not make out," she said. "And also it felt like he was almost in relief."

Creech, who has been on Death Row for more than 40 years and was to have been the first person executed in Idaho in 12 years, was sentenced to die for murdering his cellmate in 1981 with a battery-filled sock.

He was imprisoned at the time after being convicted of five other murders, although he claimed to have committed dozens more.

There have been a number of botched executions in the United States in recent years, including a failed attempt in Alabama in November 2022 to execute convicted killer Kenneth Smith by lethal injection.

Smith was eventually put to death in January of this year in the first execution in the country to be carried out using nitrogen gas.

Most of the botched executions have involved difficulties in inserting the IV needles that deliver the lethal drugs, according to the Death Penalty Information Center.

'Time is running out'

A Texas man is also scheduled to be executed on Wednesday for a double murder he insists he did not commit, in a case that has drawn the attention of the Catholic Church and celebrities Kim Kardashian and Martin Sheen.

Ivan Cantu, 50, was convicted in 2001 of the murders of his cousin James Mosqueda and Amy Kitchen, Mosqueda's fiancee, who were shot to death.

Cantu's then-fiancee, Amy Boettcher, who has since died, testified at his trial that he had admitted committing the murders and took her to Mosqueda's home afterwards to look for hidden drugs and cash.

Among the evidence submitted at the trial was a pair of jeans with blood from the victims that was found in Cantu's kitchen trash can.

Lawyers for Cantu maintain that Boettcher lied on the witness stand and the jeans, which were too large for Cantu, were planted in the trash can.

Cantu has steadfastly proclaimed his innocence and said the murders were carried out by a drug dealer to whom Mosqueda owed a substantial sum of money.

The Texas Catholic Conference of Bishops has urged that the execution be halted because of "serious uncertainties" surrounding the case.

Kardashian, who has been active in prison reform, urged Texas's conviction integrity unit to look into the case. "The time to act to save Ivan Cantu is now!" she said in a post on X.

Sheen, an opponent of the death penalty, made an appeal on Instagram for people to sign a MoveOn.org petition urging Texas Governor Greg Abbott to grant a stay of execution. The petition has drawn 150,000 signatures.

"Ivan was wrongfully convicted of murder more than 20 years ago," the star of "The West Wing" said. "Time is running out."

Capital punishment has been abolished in 23 US states, while the governors of six others -- Arizona, California, Ohio, Oregon, Pennsylvania and Tennessee -- have put a hold on its use.

There were 24 executions in the United States in 2023, all of them carried out by lethal injection.

© Agence France-Presse