Buerk may be a berk but his first programme at least was spectacularly good. He spoke with Joe Darby, the American soldier who blew the whistle on the abuse of Iraqi prisoners at Abu Ghraib, in his first interview this side of the Atlantic.

Darby arrived at Abu Ghraib in May 2003.

"Within the first month I was presented with a picture by specialist Charles Graner [later sentenced to 10 years for his part in the abuse] showing a prisoner chained to a cell, naked from the waist down, with a foot on his head. The floor was all wet around him. Graner said to me, 'You know, the Christian in me knows this is wrong but the corrections officer in me can't help but love to make a grown man piss himself.'" Darby didn't think much of this at the time, assuming Graner must have staged the photo. But that December, Graner gave him a compact disc of photographs showing the full extent of the abuse of inmates. "I looked through every photo, then shut the computer off, went outside and smoked probably six or seven cigarettes. I had no idea what to make of it. I could not believe, one, that they would do this and, two, that they would take pictures of it."

It took Darby two-and-a-half weeks to make up his mind to present his evidence to the authorities.

"I realised something needed to be done but I didn't want to be the one to do it." In the end he dropped the CD in a manila envelope and handed it anonymously to the Criminal Investigations Department. Within 15 minutes, an officer from the CID was in Darby's office "trying to wear me down" to find out where the photos had come from. It took 45 minutes before Darby owned up, he said, and he did so on condition of anonymity, as he feared for his own safety and that of his family.

This is where the story took an even more sinister twist, as Darby's crucial anonymity was blown apart by none other than former defence secretary Donald Rumsfeld. Darby was sitting eating dinner at Camp Anaconda in Iraq when the US congressional hearings into the Abu Ghraib scandal came on TV. And there was Rummy, thanking Joe Darby by name for handing in the photos.

"Did you think that was an accident or deliberate?" asked Buerk.

"I don't think it was an accident. Those things are pretty much scripted. I did receive a letter from him afterwards saying he had no malicious intent and had no idea about my anonymity. . . I find it really hard to believe that the secretary for defence had no idea about the star witness in a criminal case being anonymous."

Thanks to Rumsfeld's exposure, Darby had to quit his career in the military and was forced to take his family into hiding. The army did a security assessment and reported that Darby was in imminent danger of bodily harm or death. Even his own uncle called him a traitor. He and his family were placed under military protection.

Darby wasn't surprised by the reaction. "You have people who don't view it as right and wrong, they view it that I put American soldiers in prison over Iraqis, " he said philosophically.

Next Tuesday, Buerk meets former UVF man turned peace worker Alistair Little, which could be interesting.