Tony Carruthers, 57, should have been put to death in Nashville prison for a triple murder committed in 1994.

The execution by lethal injection of a death row inmate was delayed Thursday in the United States when staff could not find the inmate's vein, according to authorities.

Tony Carruthers, 57, should have been put to death in Nashville prison, in the state of Tennessee, for the murders of Delois Anderson, his son Marcello Anderson and Frederick Tucker, killed in 1994.

The Tennessee Department of Corrections indicated that medical personnel had set up a primary IV line to administer the lethal substances, but were unable to find a vein for a second injection route.

"The execution was then cancelled," the department added in a statement.

Tennessee Governor Bill Lee granted Tony Carruthers a one-year reprieve. Carruthers has already spent more than thirty years on death row and has always maintained his innocence.

Stacy Rector, executive director of the anti-death penalty group Tennesseans for Alternatives to the Death Penalty (TADP), said that this "failed execution attempt was frightening" but "not surprising."

"For years, TADP has been raising the alarm about the serious problems associated with lethal injection and urging our State to demonstrate greater transparency," she added.

Meanwhile, another man, Richard Knight, 47, was executed Thursday night by lethal injection in Florida for the murder of a woman and her 4-year-old daughter in 2000.

This execution brings the total number of executions carried out in the United States this year to 14. Last year, there were 47 executions, a record since 2009, when 52 people were executed.

The vast majority of executions are carried out by lethal injection, i.e. 39 in 2025.

Five others were executed last year by nitrogen inhalation, a method used for the first time in the world by Alabama in 2024 and compared by UN experts to a form of "torture", and three by firing squad in South Carolina, for the first time in the United States since 2010.

The death penalty has been abolished in 23 of the 50 US states. Three others, California, Oregon, and Pennsylvania, observe a moratorium on executions by order of the governor.

Of the 14 executions this year, seven took place in Florida, four in Texas, two in Oklahoma and one in Arizona.