I cannot subscribe to the lone gunman theory. "Common Sense" prohibits such a subscription, in my opinion.
Bullets are not "intelligent". Neither are they "willful" nor are they "mercurial." They go where they are aimed. They do not enter a man's head, change direction and reenter from a different angle, then ricochet and enter another man's arm, and then disappear from sight until they are "found" on a hospital gurney, unmarked and bereft of blood/skin traces.
Just does not happen !
And along those lines: When Sen. Arlen Specter -- who co-authored the "magic bullet" theory -- was berating Anita Hill in the Congressional hearings over the nomination of Clarence Thomas for a seat on the Supreme Court, he asked her if she expected him to believe that a woman who was on a committee investigating the same kinds of harrassment that she was now accusing Thomas of would wait all those many years to step forward, I desperately wanted her to say, "Senator, I can't believe that you, of all people, would have trouble believing that it took me all those years. You, after all, having come up with the "magic bullet" theory, which is far less believable than anything I've said, thus far."