US convicted murderer Christa Pike is in hospital and being given "life-saving measures" after Tennessee authorities failed in their attempt to execute her by lethal injection.
The case of Pike, whose attempted execution had already been the subject of a high-profile legal battle, has raised a number of questions.
These include what went wrong, what happens next, and - for opponents of the death penalty - fresh concerns around the suffering of an inmate when an execution does not go to plan.
A review into what happened has been ordered and executions in Tennessee have been halted for the rest of the year, Governor Bill Lee said.
Pike, 50, was sentenced to death in 1996 for the murder of 19-year-old Colleen Slemmer, an attack that was perpetrated alongside her then-boyfriend Tadaryl Shipp.
She was scheduled to be put to death on Wednesday evening, local time. The injections were allowed by the US Supreme Court at the eleventh hour after the legal battle.
Pike was given two syringes of the drug pentobarbital, though her legal team said these failed to stop her heartbeat and that she could still be heard snoring.
The Tennessee Department of Correction defended the method it used, saying "the protocol does not allow for additional procedures beyond what was carried out this evening".
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 have yet to provide their explanation of why the dosage given to Pike proved to be non-fatal, although medical experts have provided theories of their own.
Dr Joel Zivot, a professor at the Emory University School of Medicine, told the BBC he had been retained by Pike's legal team as a medical expert and that Pike probably never achieved a sufficient blood level of pentobarbital to cause her breath to stop or heart failure.
The state correction department added that Pike had been taken to an off-site medical facility.
One of her lawyers said she was "being provided life-saving measures" in hospital.
Her health status is unclear as of Thursday morning.
In his emailed comments to the BBC, Zivot said: "It's very possible that as a consequence of the delay of the beginning of resuscitation she will have a brain injury."
A third-party review has been ordered by state Governor Bill Lee, who said on Thursday that Tennessee will halt executions for the rest of the year.
This could impact any additional attempt by the state to execute Pike in the near-term, if she does regain consciousness. Her current state is not clear.
May Martinez, the mother of Colleen Slemmer who had pushed for Pike's execution to take place, told NBC News the events had been "a mess".
Opponents of the death penalty have similarly been quick to react.
Maya Foa, the chief executive of international legal organisation Reprieve, said: "We cannot know exactly what went wrong, because so much happened behind a curtain – lethal injection relies on secrecy at every stage, to hide the violence of the state taking a human life."
Authorities are yet to say whether they will try again to execute Pike. There is a historical precedent of authorities making a second attempt to execute those on death row.
Meanwhile Shipp, Pike's boyfriend and co-defendant, remains in prison, having been spared the death penalty under state law. He was 17 at the time that Slemmer was killed.
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 - which took place under the presidency of Joe Biden - raised concerns about the drug's potential for "unnecessary pain and suffering".
His 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 Department of Correction has not specifically addressed an allegation from Pike's legal team that the pentobarbital it used was "degraded". Drugs may degrade for a number of reasons, including if it has aged beyond its use-by date and its potency has decreased.
The department issued a broader defence of its method, writing in a statement: "The lethal injection chemical in the protocol has consistently been effective."
Some manufacturers have explicitly said they will no longer produce pentobarbital or will restrict their use in executions, according to Alexis Hoag-Fordjor, Co-Director of the Center for Criminal Justice at Brooklyn Law School.
In 2024, for instance, the manufacturer Absolute Standards said it would no longer make the drug., external
"It's unclear, the quality and the effectiveness of the drug" used in Pike's execution, Hoag-Fordjor told the BBC, given how difficult it has been for states like Tennessee to obtain pentobarbital. "It shouldn't be a surprise something went wrong."
The predicament Tennessee authorities found themselves in - having to call emergency medical services to save Pike after trying to kill her - suggested there was "no plan in place" for a scenario like Pike's, Hoag-Fordjor said.
"It's just such a bizarre reality to continue with capital punishment."
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 to administer a lethal injection. He was given a one-year reprieve by Governor Bill Lee.
More widely across the US, the issue of botched executions continues to cause alarm.
In 2022, more than a third of executions in the US were botched or highly problematic, according to the Death Penalty Information Center (DPI) - an organisation that provides statistics and research on the death penalty but does not take a stance on it morally.
The DPI says lethal injection has the highest rate of botched executions.
An incident in Oklahoma in 2014 gained particular notoriety. The execution of Clayton Lockett was postponed after 20 minutes because the lethal injection of three drugs failed to work properly when one of his veins ruptured, and he went on to writhe and shake uncontrollably.
In the US, 27 of the 50 states have the death penalty under state law. The federal government can also carry out executions after President Donald Trump, a supporter of capital punishment, ended a moratorium last year, However, it is yet to actually carry out any executions since then.
