Where Was Oswald During the Assassination?

The most important conclusion of the Warren Commission (WC) concerning the assassination of President John F. Kennedy is that Lee Harvey Oswald was at the 6th floor window of the Texas School Book Depository (TSBD) and fired three rifle shots at the Presidential motorcade. But this conclusion falls apart completely if Oswald was actually on the second floor just after the shots were fired (he was) or even, perhaps, in the first floor doorway watching the motorcade at the very moment of the as...