What happened in the failed execution of Christa Pike - and what next?
US convicted murderer Christa Pike is in a critical condition in hospital after Tennessee authorities failed to execute her by lethal injection, her lawyer says.
The case of Pike, whose attempted execution on Wednesday had already been the subject of a high-profile legal battle, raised a number of questions, including what went wrong? And what happens next?
A third-party review has been ordered by state Governor Bill Lee, who has halted executions in Tennessee for the rest of the year.
How did it go wrong?
Pike, now 50, was sentenced to death in 1996 for the murder a year earlier of 19-year-old Colleen Slemmer.
Pike was scheduled to be put to death in Tennessee on Wednesday evening local time. The injections were allowed by the Supreme Court at the 11th hour.
Pike was given two injections of the drug pentobarbital, but her legal team said these failed to stop her heartbeat and that she could still be heard snoring.
The Tennessee Department of Correction has defended the method it used, saying "the protocol does not allow for additional procedures beyond what was carried out".
The state protocol does not clearly specify what should happen if an inmate remains alive after a second dose, according to the AP news agency.
Authorities are yet to say whether they will try again to execute Pike. They have not explained why the dosage given to Pike was non-fatal.
Opponents of the death penalty said it was difficult to know what went wrong, because part of Pike's execution happened behind a curtain.
Maya Foa, the head of international legal organisation Reprieve, said: "Lethal injection relies on secrecy at every stage, to hide the violence of the state taking a human life."
What happens next?
The Tennessee correction department said Pike had been taken to an off-site medical facility, while one of her lawyers said on Wednesday that she was being given "life-saving measures" in hospital.
On Thursday, lawyer Randy Spivey told reporters: "We don't have a sense of her prognosis or much update on her health at the moment."
Dr Joel Zivot, a professor at the Emory University School of Medicine, told the BBC in an email: "It's very possible that as a consequence of the delay of the beginning of resuscitation she [Pike] will have a brain injury."
Historically, the US Supreme Court has not halted second attempts at executions, said John Mills, a lawyer who works with inmates sentenced to death.
In 2024, it allowed Alabama to proceed with a second execution of Kenneth Eugene Smith, using an experimental oxygen deprivation method, after their attempt to kill him by lethal injection failed two years earlier.
A Supreme Court case from 1947 allowed the state of Louisiana to send Willie Francis, a teenager whose first execution attempt failed when he was 17 years old, back to the electric chair.
The court found a second execution would not violate the Constitution's prohibitions against double jeopardy or cruel and unusual punishment and Francis was executed aged 18.
"If the question is, is it likely the federal courts would intervene in a second attempt? I'm afraid the answer is a resounding no," Mills said of Pike's case.
What is pentobarbital?
Pentobarbital is a potent sedative that slows down the body, including the nervous system. Doctors sometimes use it as a treatment for certain conditions, but in high doses it can also be used as a lethal injection to cause death.
Its use in lethal injections came under renewed scrutiny last year after a US federal government review during the Biden administration raised concerns about the drug's potential for "unnecessary pain and suffering".
The Biden government banned its use in federal executions, but that did not bind individual states such as Tennessee, which can choose their own methods.
In recent years, states have found some drugs needed for lethal injections harder to come by, because pharmaceutical companies have opposed the use of their products for such purposes.
The Tennessee correction department has not specifically addressed an allegation from Pike's legal team that the pentobarbital it used was "degraded".
But the department said in a statement the lethal injection chemical had "consistently been effective".
Has this happened before?
The attempted execution of Pike was not the first in Tennessee in 2026 that did not go to plan.
The execution of Tony Carruthers, who was convicted of kidnapping and murdering three people in 1994, was postponed in May after staff were unable to find a vein for a lethal injection. He was granted a year's reprieve by the governor.
In 2022, more than a third of executions across the US were botched or highly problematic, according to the Death Penalty Information Center.
Family handoutWho was Colleen Slemmer?
Colleen Slemmer's killers met at a job training camp for troubled teens.
She was found with an inverted pentagram - a symbol associated with satanic groups - carved into her chest.
Pike had accused Colleen of insulting her and trying to steal her then-boyfriend, Tadaryl Shipp, who was 17.
Two other residents at the camp later testified that Pike had bragged about the murder and showed them a piece of Colleen's skull.
Colleen's mum, May Martinez, drove 11 hours from Florida to attend the execution, she told People, alongside with her husband Raul.
She said: "I wanted her [Pike] to remember who Colleen was and what they've done and never forget that thought, no matter where she goes."
Shipp was given a life sentence with the possibility of parole and he remains in prison.
He was spared the death penalty for his part in the attack because he was not yet legally an adult at the time.
Correction 1 October: This article originally referred to the inmate executed by the state of Louisiana in 1947 as Willie Smith. We have amended the article to make clear that his name was Willie Francis.
Tennessee Department of Correction