If it's done all by hand to hand that does leave a trail retraceable by close analysis of human residue on the package(s). As well as bio-pinpoint those who need to be squeezed, one by one up the channel. To break that tracking or to at least hinder it, one or more "handoffs" needs to have been done by postal or some other non-specific human transition. And the serial container(s) would have needed to be sanitized or their outer covering removed without leaving detectable residue. Presumably there will be broadcast a bit of disinfo about untraceability to gain time for the backtracking to occur. Perhaps being withheld for a longer period to give the illusion backtracking is not possible. Then cometh the helldog UAVs, perhaps loaded with data to sniff the backtrack , enhanced beyond the capability of bloodhounds. Have there been reports on where the CIA or other operators of the UAVs are located? How far away can they be and remain in control? Are they located at the bases of the aircraft or some distance from the base, closer to targets. Are there on-site or nearby human spotters similar to forward controllers for artillery and aircraft? Or do other UAVs serve this role along with what the attacking UAV reports about itself, subject to bragging about kills?