Warning: Contains images some may find upsetting.
A computer scientist at a university in the north of England is studying an image of a corpse - attempting to solve a mystery that has gripped the Middle East for nearly 50 years.
This is what he looks like now? asks Bradford University's Prof Hassan Ugail doubtfully. The digitised photo is of a decomposed face and it is about to be run through a special algorithm for our BBC investigation.
The original photo was taken by a journalist who saw the body in a secret mortuary in the Libyan capital in 2011. He was told then that it could be charismatic cleric Musa al-Sadr, who vanished in Libya in 1978.
Sadr's disappearance has spawned endless conspiracy theories. Some people believe he was killed, while others claim he is still alive and being held somewhere in Libya.
His followers gave him the title of imam, an unusual honour for a living Shia cleric and one bestowed on him in recognition of his work on behalf of the Shia community. His mysterious disappearance has added to his emotional power because it echoes the fate of the hidden 12th imam, who disappeared in the 9th Century. Twelver Muslims believe the 12th imam did not die and will return at the end of time to bring justice to Earth.
Sadr's impact on the Middle East was significant; some believe he was about to influence Iran and the region in a moderating direction when he vanished just before the Iranian revolution.
During a visit to Libya in 2011, journalist Kassem Hamadé encountered a secret mortuary and found 17 bodies, one of which resembled Sadr. The follow-up investigation at Bradford University led to a facial recognition analysis that awarded the corpse a score implying a high probability it was Sadr. Despite skepticism from family and political figures, the analysis could reshape the understanding of this influential historical figure's fate.
