On the kidnapped soldier in Iraq

The US installed checkpoints in Sadr City that the US claimed were to find abducted US soldier Qusay al-Taayie. Sadr declares a general strike and Maliki orders the US checkpoints pulled. Now, we get this,

Caldwell said there was "an ongoing dialogue" in a bid to win the soldier's release, but he would not say with whom or at what level.

Is the US negotiation with/through Maliki's government/Sadr, and, what exactly are the terms of negotiation from the US, money, weapons, prisoner release, limits on future actions?

(One note, I've read several allusions around this story that the US was trying to locate Abu Dera, the infamous death squad leader. After previous raids trying to locate Dera, Sadr's political group and Maliki have registered loud complaints.)