This is just the point. The parents had shared custody for years, the divorce was 5 years ago. The custody had changed recently due to the mom moving several hours away. WHY would he have a motive to murder his son? It makes no sense!
All this talk of him having problems dealing with his ex moving on with her life is only speculation, it's not fact. They both admit they don't see eye-to-eye, but how many divorced couples do? If they all got along, they wouldn't be getting a divorce!
There is a history of violence but not towards his kids, only of his older son beating him up. Many men will hit and beat their wives but treat their children very well and would never dream of hurting one.
I don't get why the man would have any motive, that's all. Did he ever pursue getting full custody of Dylan?? Since he works out of town a lot, would he even want to have him there full time? It's not making sense to me.