Oscar Lyons' Predisposition to Violence

Oscar is a prime suspect because he's already shown that he has a predisposition to violence towards Grace. He said September 19th, he had whiskey with Grace and John at her house. So he is literally placing himself at the crime scene the night that likely Grace was killed. Does this seem smart to you? It doesn't seem very smart to me for him to do that. Unless he's telling the truth. And he has nothing to do with Grace's homicide. Butchers and surgeons should not be given preferential treatment when looking at suspects.