This was not a bad read at all, until a few weaknesses began to show later on. Miss Marple seems to have been inserted awkwardly just to appeal to fans, since she doesn't show up until later, and she doesn't really contribute anything, except by way of deus ex machina -like prescience. Also, the clue that clinched it had to do with someone throwing something out the window into the bushes right next to the house, which was a stupid thing to do since that should have been the first place the police looked. So, dumb criminal. Also, I say "should have been" because the police apparently didn't look there for days, which conveniently timed the discovery of this clue for later in the story. Dumb police.