Ah HA! its very simple, you see it may have been the knight bringing the knife in the cottage but you see when he got inside he used it to cut the banana open because the officer couldnt open it with his hands. (why else yould he have had the banana in the picture ) So when the captain finished cutting it open the peel fell on the floor, the captain triped on it releasing the knife, and it fell right on him! its so simple! its the captain who kille himself!