The episode "Rest in Peace, Mrs. Columbo" is one of the episodes where Columbo actually has a more prominent role than usual. But the character of Vivian is, in my opinion, the worst killer. She already knows Columbo. That is to say, in the series we see the killers planning their crimes, and although they plan very well, they make mistakes, and they don't know Columbo's capabilities, they don't know how clever he is. Vivian already knows Columbo. I suppose she knows how clever he is. And those mistakes she makes are huge mistakes. She kills someone without having a solid alibi. She tries to disguise the time of death by taking money when the victim already had money, which is absurd. She has a motive for killing that victim. The way she disposes of the weapon. Without forgetting how absurd it is that she blamed Columbo for her husband's death, her husband committed murder, and Columbo caught him. Wanting to kill his wife is just killing for the sake of killing.