Oswald's body language when he said "I'm just a patsy" is angry but not worried because he knows he can prove where he was. Then they killed him.
Sure, Jan. He also had a smirk on his face in the official mugshot. Looked pretty pleased with himself, he did. Also gave that defiant raised fist communist salute in a photo whilst being paraded in front of the press.
Why did Oswald leave the book depository immediately after the shooting? I believe there was likely a second gunman.