My favourite one is where Johnny Cash drugs his wife in a plane and parachutes out to make it look like an accident*. Columbo tricks him into revealing where he stashed the parachute but his parting line is (approximately) 'nobody who can sing like that can be all bad'. Moral: you can get away with anything if you've got a few good tunes :D

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* - 'Swan Song': https://columbophile.com/2020/04/04/5-best-moments-from-columbo-swan-song/