I posted this in the theory thread but think it also fits into the search and whats happening so I'm posting it here as well.
Since Misty had been on a 3 day binge and didn't want to babysit that night, maybe Ron gave Haleigh something before he went to work to get her to sleep, since Misty was recovering from her wild weekend. Haleigh got sick, vomited or peed her blanket, Misty was calling Ron telling him. GGS came over to try and help. Haleigh died, they didn't take her to the hospital because they were illegal drugs and Ron gave them to her. Maybe she tried giving her CPR, which is what junior saw the couch bouncing, Ron called Tommy and had him and Joe go help dispose of Haleigh, probably threatened them if they did not,they put Haleigh and blanket in a garbage bag and throw her out at the dock. Ron stayed at work for an Alibi and stopped at the store on the way home because he knew it had a camera. Ron tells Misty we will say she was kidnapped, he flushes or gives Tommy and Joe the druggs he has at the trailor used on Haliegh. They are all involved I think possably Timmy to.
Tommy started going down hill along time ago, I think he was going to crack way back then and thats the reason for the rat thing. I think Tommy is the weakest link and he now gave it up, they confronted Misty and told her they know what happened and she thought they were bluffing so they took her to the scene to show her and try and get her to talk.