This one is a simple story in my book. A guy found a bag. Called it in, first day did not get the response he thought he should. Called back, got ignored. Called back the third day, finally got a police officer, who went out to the scene, and obviously did not do a good job, but assured this meter reader everything was fine. The meter reader got reassigned and then managed to get back to this area. He went out to pee, like he always did when he was here, (In Dec.)and he saw the bag again. He decided he would be brave and look. What would it hurt, the officer told him that it was nothing. A skull fell out and he realised that officer didn't do his job. This guy is a good guy. An average guy working for a utility company. I am glad he stuck to it and opened that bag.
I know as sleuths we get all caught up in explainations, but sometimes a bird is a bird, a frog is a frog, and a killer is a killer. Just because the explaination is boring as rotting wood, does not mean it is not the right one. They will be able to tell how long the body has been there.
As for Casey's guilt, this makes perfect sense to me. KC took her close to home, not far out, and did a shaby job of covering her up. KC did it for three reasons. First she only caring for herself, did not care about properly disposing of the body. Second, KC did not deem her daughter worth the sweat and effort to bury the body deep, if at all. Basically KC did not want to work, not even for this. Third, KC thought she could use the idea that there was no way, a mother would do this to her child and be stupid enough to dump it close to the house.