Fantastic to know that like all good corporations, the US military believes in outsourcing activities that aren't core to it's mission. Quotes from an article in the Guardian:
"We know that CACI and Titan corporations have provided interrogators and that they have in fact conducted interrogations on behalf of the US and have interacted the military police guards at the prison," he said.
but the shocking thing is they seem to operate outside the law:
"It's insanity," said Robert Baer, a former CIA agent, who has examined the case, and is concerned about the private contractors' free-ranging role. "These are rank amateurs and there is no legally binding law on these guys as far as I could tell. Why did they let them in the prison?"