I hate to say it, but the way to feel safer is to do something yourself. You not walking the river, will just make the river that much less safe for everyone else. Get together with those nice neighbors and discuss things. Watch out for each other. Be out after dark (in groups). Neighborliness is not a passive system.

Relying on 'they' to catch the perp will make it less likely to happen, and slower. And more important you will not feel safe as a result. If you are involved, you will feel that not only did you take care of this problem, but the next one won't scare you as much.