The execution of a convicted killer in Ohio has been postponed after he asked to donate some of his organs, including a kidney to his ailing mother.
Ronald Phillips was due to be executed by lethal injection on Thursday for the 1993 murder of a three-year-old girl.
Ohio Governor John Kasich said that if the donation could save another life it should be allowed to happen, but that it was "uncharted territory".
Doctors must now assess whether pre-execution transplants are feasible.
Phillips, 40, was sentenced to death for the rape and murder in 1993 of Sheila Marie Evans, his girlfriend's daughter.
He had been due to be killed on Thursday by use of the drugs midazolam and hydromorphone, the first time in the US that that particular drug combination would have been used in an execution.
Ohio state decided to go ahead with the new lethal cocktail because it did not have enough supply of the commonly used drug pentobarbital.
On Monday, after Mr Kasich rejected his plea for clemency, Ronald Phillips made a request to donate organs or tissues, prior to his execution.
His lawyers said the request was not a tactic to delay his execution, but an attempt to do good.
Phillips's mother is reported to have kidney disease and his sister has heart problems, but he has said he wants to donate his organs to "as many people as possible".
The execution has been rescheduled for 2 July next year, to allow doctors to determine whether it is feasible for Phillips to donate his non-vital organs - which could include a kidney - before returning to death row.
While the donation by death row prisoners of non-vital organs is permissible in the US, the donation of vital organs is not allowed under US law.
"I realise this is a bit of uncharted territory for Ohio, but if another life can be saved by his willingness to donate his organs and tissues then we should allow for that to happen," Mr Kasich said in a statement.
Richard Dieter, director of the Death Penalty Information Center - which opposes executions - said that while it is not unprecedented for death row inmates to donate non-vital organs, a stay of execution has never been granted to allow it.
"If the whole idea is to save a life, there's one life to be saved simply by not executing the person at all," the Associated Press quoted him as saying.