Tennessee Governor Bill Lee has halted the remaining execution scheduled in the state this year after an attempt to put Christa Pike to death failed.
Mr Lee has ordered a “comprehensive, third-party review” to establish what went wrong during the execution attempt.
In a statement, he said: “Carrying out a lawfully imposed sentence is among the state’s most serious responsibilities, and the people of Tennessee expect it to be done in a manner that is not only legal and constitutional, but is effective.”
Christa Pike execution attempt
Pike was reportedly left snoring loudly after two unsuccessful injections. Witnesses said she had not lost consciousness and that her heart was still beating.
She was taken from the prison by ambulance. Her current condition is not known.
The execution had been allowed to proceed after the US Supreme Court lifted a stay issued by a federal appeals court.
Pike was convicted of killing 19-year-old Colleen Slemmer in 1995, when Pike was 18.
