[monocle]

Zawahiri could have been injured and lost a leg or an arm and still escaped. There were reports some bodies(perhaps injured but still alive) were removed before authories arrived at the scene. Body parts at the scene would increase the probability of Zawahiri's present at the time of the bombing, but unless there is evidence of vital organs there is still the probability he escaped injured.

[Coop]

but unless there is evidence of vital organs there is still the probability he escaped injured.

Gosh, why didn't I think of that?

[Cheburashka]

I said the odds of survival go down, I didn't say they were nil.
Obviously, if they find the tip of a finger, it isn't definitive proof that he was killed.
If they find most of a limb, he would need immediate high quality medical attention even if he survived the immediate explosion(s). Something he would be unlikely to get.
I think we can both think of body parts that would indicate demise with over 99.9% probability, but since people of delicate sensibilities, such as children, might be reading this, I will say no more.