Hear me out here: I don't actually find this all that disturbing. Sad, yes. Disturbing or meaning he is psychotic? No.
When you grow up on a farm, or in a farming community, you learn not to become too attached to animals, especially those that are useful in some way. For example, I have friends who have "pet" cows, but they know someday they will slaughter those same cows for dinner. It doesn't make them killers. They are saddened by the attachment they have and yet, they understand the necessity of what they will do. We don't know the full situation of the "pet" racoon. He may have kept it with every intention of skinning at some point, thereby keeping it compartmentalized. I don't think that's inherently bad.
I am not saying BM is innocent, but I think since the AA is not released, we are all looking at things that may be benign and trying to find a reason for his behavior. IMO, there is NO reason for his behavior. I think he murdered Suzanne for money, control and power. I don't think there is anything in his past that would have predicted it because I don't think he got to that point until only maybe a year before it happened. Many folks grow up the same way as BM and are harmless. They could never imagine his mindset. And like a previous poster, I think he may even regret his actions at this point, not because he did it, but because he got caught.