They were still in our custody. While not completely improbably, I don't think these guys would be able to cause the blunt force trauma that exaccerabted their conditions, so, in that case, that means someone else did.
I sincerely hope we are not resorting to physical tourture.
... and not previous injuries, or any other likely explanation.
Dealing with the facts- they died in our custody.
Interrogation subjects should be kept alive for effective interrogation, so if their deaths were avoidable there has been a failure in our administration of these detainees that will be- or has been- investigated.