Backward pass

[chymechowder]

same situation, but instead of a pitch, A1 attempts a handoff to A3. the exchange is botched, and the ball becomes loose.

4th down fumble rules apply, right? but who has fumbled?

I've heard different things. Some say only A3 can legally recover and advance the ball. But others say A1 is the fumbler. Because if the problem occurred during the exchange (say they bumped into each other, or the ball came out as soon as A1 put it in A3's belly), then that means A3 never had possession, so therefore he can't have fumbled.