"The Warren Commission did not "cover up" for "the KGB," or for any other communist institution."
Who did they 'cover up' for, in your opinion?
Well, I have to admit that I have read a few books on the assasination, but none on the investigation. So I don't have much of an opinion on the investigation, other than that I generally agree with its conclusions. Senator Specter is too moderate for my taste, but I judge him a decent man.
The important thing about the assasination, as far as I am concerned, is who did it and, above all, what was the motive.
If you want to read an honest sceptics' view of the assasination, check out the book written by Bonar Menninger with Howard Donahue, "Mortal Error." They give the name of the fellow they think fired the fatal shot (not Oswald) and a motive (human error). This theory a person can agree or disagree with. (I disagree.) However, attacking the investigators without sticking your neck out to say precisely who the real killer(s) were is, to me, rubbish. You can poke holes in any theory if you don't have a responsibility to prove there is a more likely alternative. This is what defense attorneys do all the time, and sometimes it works because in something so complex as this, all the pieces will not fit perfectly together for ANY theory.
Spector fingered Oswald simply because he thought the evidence was strongest against Oswald and rather weak against all others. So do I. Rush to judgement? Maybe in 1963. But now all the facts are in after many exhaustive investigations, governmental and private. Argue the facts concerning who did it and why, not the government investigation.
As for there being a coup, Kennedy and Johnson had such similar, strongly anti-communist, policies that this is ridiculous. The liberals who doubt Kennedy would have defended South Vietnam do not know much about Jack Kennedy.