Yep, the problem is that like it or not, we're all trained to believe what our governments and government officials tell us to believe, so if they say that Lee Harvey Oswald was the only shooter, no matter who comes along with a credible alternative, we are trained to discredit them.
Howard Donoghue was a ballistics expert who'd worked for the FBI, CIA etc as an expert witness in several shooting investigations, and he proved beyond doubt that the shot that hit Kennedy in the head was fired from Hickey's rifle. In McLaren's book he found several witness statements that were presented to the Warren Commission that confirmed that Hickey fired his rifle, but for reasons best known to Earl Warren, this information was never acted on.
Donoghue was interviewed on US TV shortly after the release of his book in 1992, but once again, the American people have been bombarded with theories from every whacko and his dog since 1963, so when Donoghue came along with a credible theory, he was just written off as another nutbag. It's a shame that it wasn't followed up, but it worked in the US Governments favor, and deep down, the American people wanted Lee Harvey Oswald to be the shooter, to prove that the system that they've been trained to believe in, works.
That pisses me off, but that's life, you can't change peoples deep seated opinions with logical argument. Cheers, Terry.