I assume that you accept that Booth assassinated Lincoln? Apply your standard of proof used in the JFK case to the Lincoln assassination so that we can understand the difference with Oswald. Link Booth to the weapon for example. Where are the prints, pictures, documents, serial numbers, and witness testimony that link Booth to this specific pistol? Where did he obtain it from? Where did he buy his ammo? Prove to us that Booth even carried that pistol or any pistol into Ford's Theatre.
Why do you have to link a weapon to Booth? The only reason you
try to link a weapon to Oswald is that you have nothing else.
An entire theater box full of people saw him standing there with a derringer immediately after Lincoln was shot and they knew him. Rathbone fought with him and was stabbed by Booth. An entire theater full of people who knew who he was saw him leap from the box shouting "Sic Semper Tyrannus". He had accomplices who ratted him out. He had a diary in which he said he did it.
The only way this would be the slightest bit analogous is if Lincoln keeled over and nobody saw anybody or anything, but a derringer was found elsewhere in the theater an hour later and a photo turned up of Booth holding a little gun that may or may not have been the same gun.
It doesn't freakin' matter whether anybody can prove if Booth bought the weapon, because that's not evidence that would prove who killed Lincoln.
"I walked with a firm step through a thousand of his friends, was stopped, but pushed on. A colonel was at his side. I shouted Sic semper before I fired. In jumping broke my leg. I passed all his pickets, rode sixty miles that night with the bone of my leg tearing the flesh at every jump. I can never repent it, though we hated to kill. Our country owed all her troubles to him, and God simply made me the instrument of his punishment." -- John Wilkes Booth
"I didn't shoot anybody, no sir. I'm just a patsy". —Lee Harvey Oswald