Chinatown Robbery - Spoilers

So Harry and Quan just happen to come across the robbery. By an amazing coincidence, Dean Madison just happens to be there, and gets killed. He happens to be carrying a copy of the dead pool, which Quan happens to read.

But this amazing stroke of luck doesn't help them solve the case. They apparently don't connect Madison with Peter Swan and only find out about the dead pool from TV.

Why put this in there, apart from another change for Dirty Harry to shoot people???