Ending of AOC

I really enjoyed the book, but did Charmey have to die so suddenly? Why couldn't they have found the guy who did it instead of letting the murderer off the hook? All in all, a good book, with some people with real problems, but I feel that the only person who made a dramatic change in their life was Frankie, perhaps she could have had Yumi make a more significant change in her life. That's just my opinion.