> As an aside, have McCain's claims of being tortured ever fully been
> investigated?
I think this is an odd question to ask; John McCain's capture and imprisonment was a widely reported event at the time, seeing as how his father was the commander of all US forces in the Vietnam theatre, which made him a prime propaganda target. His story was widely documented and told long before he left the service (1981); implying that it might be a political move is pretty low.
I suggest The Google can answer your question.
/jordan