Iran's judiciary chief, Ayatollah Sadeq Larijani, faced competing calls on Thursday whether to spare a convicted drug trafficker who survived the gallows.
The prisoner, identified only as Alireza M., 37, was pronounced dead by the attending doctor after spending 12 minutes hanging from the noose suspended from a crane in a jail in northeastern Iran.
But the following day, staff at the mortuary in the city of Bojnourd where his shrouded body was taken discovered to their shock that he was still breathing.
He is now recovering in hospital while jurists argue over whether the law requires that he be taken to the gallows a second time.
Amnesty International called for an immediate stay of execution for Alireza M. and for all other death row prisoners in Iran, which carried out more executions last year than any other country bar China.
"The horrific prospect of this man facing a second hanging, after having gone through the whole ordeal already once, merely underlines the cruelty and inhumanity of the death penalty," the watchdog's Middle East and North Africa programme director Philip Luther said.
"The Iranian authorities must immediately halt Alireza M.'s execution and issue a moratorium on all others."
Iranian jurists were divided over what should be done.
One high-ranking judge, Nourollah Aziz-Mohammadi, told the Iran newspaper the law required that the convict be put to death, and that he should be taken to the gallows a second time.
"When a convict is sentenced to death, he must die after the sentence is carried out," Aziz-Mohammadi said.
"Now that he is alive, we can say the sentence was not carried out and must be repeated."
But other lawyers signed a petition to the judiciary chief appealing for a stay in the exceptional case.
"In our law, nothing has been said about a person who survives hanging after 24 hours," one signatory, Abdolsamad Khoramshahi, told the paper.
"Since the sentence was carried out, there is no reason to repeat the sentence."