So here is my theory so far. As we all know the burglary was staged and that Kelly OD'ed on oxycodone. Now I haven't figure out where she had gotten them yet, possible Kenny or even Karen. We know Kelly had a prescription for percocet but not oxycodone. According to Karen she got her pills (not sure what they are yet) from Kenny, so we can assume he is still dealing. I'm thinking that Karen realised that Kelly had a pill problem and went behind her back and either told Russell or one of their friends of her suspicion. Then Kelly found out and caused the fight between these two friends. On October 30, Karen called Kelly twice and talked a total of 15 minutes. I believe Karen went over to Kelly's home found that Kelly had over dosed. I believe Russell stated the scene with Karen's help.
This is just my starting theory and I'm interested to see how close I am once more evidence come out.