two questions (spoilers)
1. The Tuchman Marsh guy was following Harry throughout the entire movie. So one would expect that he followed him when he loaded Chad's body in his car and dumped it in Chesapeake Bay. After all, the CIA guy following him (or watching Cox's apartment) saw him. So what's with that? Are we to think it happened? If not, why not? If so, why no consequence?
2. Why would Linda think Chad might have 'gone over' to the Russians, or been taken by them? Last she saw of him, he was off to break into Cox's house and steal 'important' secrets. Cox has already done violence to Chad. Surely her assumption would be that Cox, in collaboration with the CIA, captured him at Cox's place and either killed or took him. Or am I missing something?