The in flight camera is usually attached somewhere on the wing leading edge, not accesible in flight. However, he certainly could have landed, pulled the card and buried it or smashed it. Pretty lousy of him to swallow it, I guess guilt got to him and he squealed.....or maybe a little pressure from the police investigators?
He blew it and needs to take full responsiblity. This would be an awful thing to live with in so many ways.
It will be hard to live with, knowing you might have been at least partially responsible for a deadly accident through negligence.