It wasn’t a big island and it wasn’t far from the mainland. In many ways it was just another suburb of its parent coastal town. But it was enough of an island to give its inhabitants a sense of a separate identity. They wouldn’t go so far as to tolerate a murderer in their ranks but there was a reluctance to have police from the mainland digging through the complicated network of island relationships.
Maybe this was why they didn’t immediately report the finding of the first body.