Genius: More like idiots

I wonder why the makers of this gave it the title Evil Genius when both Bill and Marjorie clearly were anything but that. Fortunately for the pair, the detectives were even more stupid not following a handful of clear leads given to them. We are told time and time again that they are extremely intelligent. Why? There is nothing here that makes them intelligent. Is it intelligent to leave a drawing of the bomb you just made on top of something else in your garage, then call the cops to report there is a dead body next ot it before removing said note first? Luckily for Bill the cops were even more stupid not catching this... This was a high profile case so you'd think the detectives would follow up on each and every lead. Imagine how "hard" they work when it is not a high profile case. Great to know where our tax money is going...