So you are saying that Pakistani officials were on the scene at the time of the bombing? I know I wouldn't be searching a village for Zawahiri when I know that there are bombs about to be dropped on it. That leaves two options. 1. The testimony of the local villagers which is unreliable if they are sympathetic to Zawahiri or 2. You know for a fact he wasn't there because you know his location.
Option #2 is more likely. Back during the early Spring of '04, the Paki's went into Whaziristan villages (uncontrolled tribal area in Pakistan on the border with Afghanistan where we think #1 & #2 are hidding) and allegedly took out senior AQ types. They telegraphed their move days ahead and never showed any evidence of capturing/killing any prominent AQ types. Read show of force to pacify us after Powell's visit. Problem is we have no permission from Musharaf to conduct operations on his side of the fence.