Death row inmate Christa Pike is unconscious and on a ventilator in hospital after two failed execution attempts in Tennessee, her lawyers said.
Hospital staff were working to save her life and clear two doses of the drug the state uses to execute prisoners, they added.
In a court filing, Pike's legal team said problems with the IV lines caused the lethal drug pentobarbital to go into her body, instead of her bloodstream.
They wrote: "Apparently at no point did any member of the execution team realise that the IV lines were not correctly placed or that the veins had blown and that the pentobarbital was, in whole or in part, entering Ms Pike's body."
Instead of "remedying this failure", they prepared and administered a backup set of pentobarbital syringe, the lawyers added.
The execution team worked for an hour to administer the lethal drugs, said Pike's defence lawyer Randy Spivey, who counted at least seven needles in her left arm.
She was still snoring when the execution chamber's microphone was cut off more than an hour into the execution attempt.
"Preserving this evidence is essential to understanding what happened, ensuring accountability and protecting Christa's legal rights," two of her lawyers said in a statement.
State officials have not offered any explanations about what went wrong.
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Death row inmate critical after failed execution
Tennessee Governor Bill Lee ordered a review of the state's execution procedures and indefinitely postponed Pike's execution and another one slated for this year.
Pike, 50, has suffered significant injuries to both her arms, her lawyers have said, and is in a critical condition following the failed execution on Wednesday.
She was taken by ambulance from Riverbend Maximum Security Institution in Nashville.
Maya Martinez, the mother of Colleen, expressed frustration over the failed execution, saying on Thursday: "I didn't get justice for my daughter."
Pike was convicted of killing her 19-year-old classmate Colleen Slemmer in 1995, when she was 18.
Following the killing, Pike was diagnosed with bipolar disorder and post-traumatic stress disorder, her lawyers said.
She had been scheduled to be the first woman executed in Tennessee in more than two centuries.
(c) Sky News 2026: Christa Pike: Death row inmate unconscious and on ventilator after botched execution, lawyers
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