That book was used to discredit other theories but doesn't close the case at all. The Tramps were a curious bunch, one included Woody Harrelson's father who was a hitman. Kennedy got hit from two sides at least and there are some books that speculate that there were three hit teams in place that day, excluding Oswald.
I'm sorry, but "Case Closed" sealed it for me. And the way I see it, if their really was a conspiracy, the truth would have come out for certain by now, instead of just the continued speculation.
Oswald acted alone, and that's that.
If you know anything about shooting, all you gotta do is watch the Zapbruder film to know that the shot that blew Kennnedy's head apart came from his front-right.
That makes at least 2 shooters since the first shot got him in the back.
How many people does it take to kill a man?