Well, again.. I don't think there is evidence that points to anyone else because the police didn't want it to be anyone else. At the very least the roommate and ex-boyfriend should have been investigated hard because as said the roommate didn't call in that she was missing for four days and the ex-boyfriend the defense team found he had access to her voicemail and we know that some messages were deleted. He probably erased threatening messages.
Also, the boyfriend had access to the Avery's property because he was on the search team. Would it have been impossible for him to park the vehicle and dump the bones? I don't think so.
I think it's possible he and the roommate had something to do with it and the police planted evidence to bolster the case.
It's reasonable to assume that the key, blood in the vehicle and bullet were all planted. None of the police stories add up AT ALL but we are supposed to believe them why? because they wear blue? fukk THEM.