Why do CPR on a dead man for 90 minutes? Stevens was the guy with all the 'secrets'. Dead men tell no tales.
You are looking at it from the U.S. administration point of view, which only tells one half of the story.
When you look at it from the Libyan attackers point of view, it opens up a lot more answers.
If they (the Libyan attackers) were trying to free Omar Abdel-Rahman in a prisoner transfer, then the ambassador (taken alive) would have been their best option.
And we know that freeing Abdel-Rahman is a major goal of many terrorists, especially those associated with Egypt.
If that is the reason they went there, to grab Stevens to trade him for Abdel-Rahman, then everything the Libyans did after the attack (i.e. taking Stevens to the hospital, trying CPR for 90 minutes) makes sense.
Without that motivation on the part of the Libyans, none of that makes sense. None of it.