Ex-Marine Joseph Hickman said Guantanamo was a “bad dream” he just wanted to forget. Source: Supplied

Army Staff Sergeant Joseph Hickman was on guard at the Cuban prison camp on the night they died, and calls the official version of events “impossible”.

“They would have had to all three tie their hands and feet together, shove rags down their throats, put a mask over their face, made a noose, hung it from the ceiling on the side of the cellblock, jumped into the noose and hung themselves simultaneously,” the ex-Marine told Vice News in an explosive video interview.

“In a cellblock where guards are ordered to check on detainees every four minutes.”

There had also been an inspection of the cellblock only a few hours earlier, Hickman said, and guards had found nothing detainees might use to make the nooses and rags.

Hickman tried for years to put the nightmare of his time at Guantanamo behind him, but eventually he was forced to confront his past.

He has now written a book, Murder at Camp Delta, which he hopes will be a step towards finding out the truth.