Ethics Hypothetical

This was proposed to me at the courthouse last week:

There is Suspect A and Suspect B. I represent Suspect B. A murder during a robbery was committed where Suspect B, my client, was in the "getaway car" and arrested. The cops don't know the identity of Suspect A who got away. Suspect B tells me, "I didn't know he was going to do that. I'm innocent. But I can tell you his name if it will help me with the prosecutor."

Now Suspect B unexpectedly dies.

There is a Crime Stoppers reward offered for the identity of Suspect A.

Does the lawyer for the dead Suspect B reveal Suspect A's identity? Does the attorney-client privilege prevent it? Could the lawyer reveal it and collect the reward?

My answer: No way I would collect the reward. But the question of going to the prosecutors and telling them who Suspect A is would keep me up at night. My now dead client wanted me to do that with the condition that it helps him when he was alive but now he is dead. Does that matter? What's the right thing to do?

This hypo comes from a movie I had never heard of. And has the great line of "I'm tired of trying to do the impossible for the ungrateful."