Nothing "evolved" if by that you mean there was a frame up of Oswald. A few details may have been left out or omitted from the initial statements as expected. Over time there was a more in depth investigation. When all was said and done Oswald's rifle was found on the 6th floor. Fired bullet casings from his rifle were found by the SN window. He fled the scene and murdered a police officer. It's a stone cold case against Oswald. To suggest that a latch on a door to the roof precludes Baker and Truly from going there after the assassination is somehow evidence of a conspiracy is laughable.
He didn't flee the scene, he just left as did (at least) 18 or 19 others.
Oswald's rifle lol. Explain why his fingerprints weren't on the shell casings, nor on the clip, nor on the bolt or trigger. Explain how Oswald or anyone else could have fired an accurate shot using the telescopic sight which was broken, needed shims to stabilize (not found or present when the rifle was discovered) and after the rifle was re-assembled using a dime.
Explain why the rifle supposedly ordered by Oswald is a different one than the rifle found on the sixth floor and now located at the NARA.
The bullets recovered from officer Tippit's body couldn't be matched to the barrel of "Oswald's revolver."
There is no "stone cold case" against Oswald. Not a single prosecutorial fact is undisputed, and with good reason. You probably think a man can not be framed for murder or any other crime. Think again bubba, it happens.