He stared at Sirius for a moment, realizing that there was no real way to stop Sirius. And while it wasn't the only way to prove Sirius' innocence, it might well be the easiest way. "He can run as far as he wants. I can find him the same way I found you." He should be able to, at least. It was possible that it could be blocked, but Peter would need help for that.

"We can't kill him, Sirius. No matter how much you want to, how much he deserves it? We need him to prove your innocence. Then he can go to Azkaban, just the way he should."