The Lovely Bones - Alice Sebold.

Young teenage girl Susie Salmon is murdered and her body cut in bits and only her elbow found. The readership know who did it because the girl's spirit/ghost remains closely and tells us so. We know that the same man has killed many other girls and occasionally women. Susie speaks to some of them in heaven. The police make no progress even though the girls father points the finger at the right chap. The girl's sister is more proactive and she becomes a new target. The police investigator is having sex with Susie's mother and allows the murderer to escape. He kills again, and is never caught - he dies in a freak accident trying it with another girl. Susie has appeared to her friend Ruth (and to her brother) and briefly changes places with Ruth so she can have sex with her former boyfriend Ray (now Ruth's boyfriend). They all live happily ever after (Ruth and Ray anyway, Susie finds a more distant heaven). Good grief. What ambition.