So you have no idea or theory what happened.
Any bozo can make up a story. Proving that it’s actually true - not so much.
Changing his shirt would not explain how the bus transfer ends up in his shirt pocket. He was not a magician who could make a bus transfer appear by putting on a new shirt.
No, but cops have been known to make things appear like magic.
It was in Oswald's shirt pocket when arrested.
Correction: it was “in Oswald’s shirt pocket” hours after he was arrested and already searched.