At the time of her death she was working on a book about the assassination to be published by Bennett Cerf's Random House.
Dorothy had interviewed Jack Ruby. She would then come to studio 52 every Sunday night and tell everyone that she was going to blow the lid off the Kennedy assassination. Within earshot was likely John Daly, whose father in law was Earl Warren, head of the eponymous Warren Commission which was investigating the assassination.
It is not unreasonable to think that Daly was leaking information about Dorothy's investigative reporting to his father in law; Dorothy's unpublished book was thus probably known about in Washington.
My personal theory is that LBJ was behind the assassination. Dorothy's book, with Jack Ruby as a primary source, could have exposed LBJ's role in the assassination. It thus became important in Washington to snuff out Dorothy and seize her notes. Dorothy's notes for the book disappeared when she was murdered.
By November, 1963 LBJ's political career was a shambles. JFK had decided LBJ would not be on the 1964 ticket and LBJ was embroiled in a scandal involving Bobby Baker. My theory has LBJ's Texas oil-baron buddies bankrolling a mob hit on the President, carried out by the Corsican mafia. JFK had been threatening to eliminate the oil depletion allowance, a big tax break which, if eliminated, would have cost LBJ's oil-baron buddies millions; they thus had an economic motive to do away with the President. Once in the White House, LBJ could grant his cronies political favors, such as keeping the oil depletion allowance in place, which he did. There was thus a political motive to assassinate Kennedy.
