...that the compartmentalized elements of the CIA that participated in 9-11 were run by sayanim.
Therefore, if we do a reverse-lookup, we will find that CIA personnel with Israeli citizenship may congregate in certain departments. Those departments are the ones that participated in 9-11.
Who within the CIA has dual citizenship? Find them. If they run a compartment, then that compartment was involved in 9-11.
The same goes for the FBI.
We're on the home stretch, everyone. The mystery is almost solved. At this point, I would turn the case over to a junior officer and go out for drinks. ...Because all that remains is the mop-up...