in the book flush In Chapter 20, why do the police need to question Noah’s father?

The cops were going to get a warrant to have Paine's casts taken off. They suspected that his hands weren't broken but rather were burned from the fire he started. Donna showed the cops the statement from the hospital emergency room which indicated he was treated for fractures not burns. And the timing on the statement showed that his injury occurred sixteen hours before the boat burned down. The cops left and never came back.