Backcourt Violation - How to handle this?

[Cornellref]

Hey all, just going over some odd situations that happened this past year. Here's one I'm not sure how to properly manage:

I am lead along the endline and A1 ends his dribble directly in front of me. He panics due to some defensive pressure and throws a backward pass to teamate A2 who is open near the Trail official. However, defender B1 slightly tips the ball after the release of the pass and it sails into the backcourt as a result. I immediately give a tip signal but my Trail is screened and I don't verbalize the tip (should I?). A2 is the first to touch it there and the Trail called a backcourt violation. How do you proceed from here? Thanks for your responses. -CRef