Six months ago Muhammed Hussein Torkaman was a young Revolutionary Guard in Iran, working in the security team attached to the supreme leader Ayatollah Khamenei and President Mahmoud Ahmadinejad.
As part of this inner security force, the Sar-Allah, or Avengers of God, he was also responsible, he says, for the leaders' personal safety during the protests after the presidential elections, which were widely viewed as having been stolen by Ahmadinejad.
He witnessed increasing dissent within the guards.
Torkaman, 24, is in hiding in a small, nondescript flat in a backwater in central Turkey, where he is seeking asylum with his wife and two-year-old son.
His extraordinary account of the depravities of the Iranian government and its crushing of dissent forms the backbone of a film by Guardian Films and the Bureau of Investigative Journalism.
The film features the testimony of four former Revolutionary Guards, and reveals the extent of the disillusionment and division within the ranks. Most significantly, perhaps, it provides evidence that sections of the Revolutionary Guard — a core part of the regime, which controls both the nuclear programme and huge swaths of the economy — are angry with the very leaders they have been traditionally prepared to die for.
Torkaman admits playing a part in crushing the opposition in the aftermath of the contested election, but he says that he could no longer live with it and fled for Turkey in January.
Fearful for his safety, he believes Iranian intelligence is tracking his movements. "Please no filming outside the flat," he says.
"It is too dangerous."