What happened to the millions allocated to rebuild Iraq? [audio 5min & 6min]

In the first year after the overthrow of Saddam Hussein in Iraq, the US-led Coalition Provisional Authority was in charge of $20 billion of what was essentially Iraqi cash, mainly past oil revenues in a fund set up by the United Nations. The money was spent. Part 1: The problem is that nobody really knows how the money was spent. There are no records for what happened to nearly half the cash. As part of a documentary series on Iraq reconstruction, BBC World Service business correspondent Mark Gregory has been following the trail of that Iraqi oil money and why is so much of it unaccounted for? Part 2: The US has now spent nearly $40 billion on the rebuilding of Iraq. In real terms, that's twice as much American taxpayers' money gone on Iraq as was spent rebuilding Germany after World War II. Many Iraqis say you'd hardly know. But, as the mood in America swings towards disengagement, it will be increasingly up to Iraqis to finance the work themselves. One thing that seems to be standing in their way, though, is corruption. Correspondent Gregory has been investigating how much of a problem it is.