Abdullah al-Zaher, who is now 19, was arrested for attending a protest four years ago and now faces execution as part of a crackdown on dissent by the country.
He was recently moved to a new cell in solitary confinement and activists fear he could be executed by beheading very soon.
Before his transfer the teenager was help with Ali al-Nimr, a fellow juvenile offender who has also been sentenced to death after his arrest at the age of 17, despite the UN issuing an urgent call to halt his execution.
Abdullah al-Zaher’s father, Hassan al-Zaher, told the Guardian: ‘Please help me save my son from the imminent threat of death.