simple solution...
burn the house down - preferably with keaton in it - make it look like an accident - clain on the insurance.
Failing that, get hold of a really big stick and batter keaton around the head with it until he is dead. Chop up the body, put it in a bag, drive the bag down to the sea, hire a boat, take the bag out to sea, attach some weights to the bag, throw it over board and watch it sink. Drive back to the house, clean up thoroughly and have a good alibi.