What are the three facts that help David realize his father is investigating the case against Uncle Frank?

In Chapter Three, David and his parents want to attend Marie’s funeral, but her family has made plans to bury her in North Dakota. Gail says they can at least send flowers, and stresses that they must do something. Wesley replies that he is doing something, and David realizes they are talking about Frank’s involvement in Marie’s death. David, accustomed to his father’s work habits, knows his father is building a case against his brother because of how charming and social his father is being. He only does this to garner good will in the community before making his arrest.