They did. They said they could only hold him for a day without charging him and wanted to talk to the victim before bringing charges. But that was 3 days ago. What's the holdup?
I bet it doesn't normally take them 3 days to gather enough evidence when someone gets shot in the head to decide to charge or not. What if the victim had died, why would they need to wait? I suspect they had decided already not to charge already and now realize they can't get away with it.