They should have just disappeared. A week or two playing water sports with the CIA and we would have extracted everything they ever hoped to know.
Yes, and they didn't, largely because we turned them over to the Iraqis who found a more pressing purpose for them than that. It could be a lot of things. There are multiple parties with interests here, and the Iraqi government is attempting to solidify its support with domestic factions who may have given guarantees in return for the freedom of these operatives. Whether these are to be trusted is something I couldn't even guess at.
The Iranians, however this turns out, badly need to be slapped down for it and I'm afraid that they won't be. My personal preference would be for "accidents" to start happening to senior members of the Revolutionary Guard, but then they already are... Our work? Ahmadinejad's? Both? Welcome to the Middle East.