The president condemns the murderers but says the death penalty at federal level "must stop".

The move could further delay the execution of Robert Roberson, who was convicted of killing his daughter but claims he is innocent.

Carey Dale Grayson became the third person to be executed by nitrogen gas in the United States.

The Texas man was meant to be executed last month, but it was temporarily stopped at the last minute.

The judiciary contradicts state media reports from 28 October that Jamshid Sharmahd was put to death.

The German-Iranian had denied leading a group that bombed a mosque in 2008, killing 14 people.

A Monday hearing in Texas could determine whether Roberson receives an ultra-rare grant of clemency.

Robert Roberson has thanked supporters for winning a temporary reprieve in the controversial case.