Who should be responsible of the mishandling of the 6.6 billion dollars in missing cash in Iraq?

In 2004, 20 plane loads of shrink wrapped cash (over 12 billion) was send by the Bush Administration to Iraq to pay Iraqi contractors after the fall of Hussein. 6.6 was unaccounted for. According to witnesses there was no or little accounting. Millions was stuffed in to Gunny Sacks and distributed.