When searching David's room, police found a large piece of cardboard with five hand drawn circular targets which had up to 29 bulet holes in and around them.
The layout of the targets also matched the layout of people in rooms in the house where they were killed.
The murders were clearly planned and this shooting board is consistent with someone who has planned something and is making the necessary psychological preparations. There are many other ways of creating a shooting target, using concentric circles of different sizes being the most common form. It cannot be just coincidence that David had a shooting target that matched the crime so closely.