Very old post, I know, but I was reading all comments regarding the "it's all in the game" episode, which I recently watched again and found interesting, and I agree it's a bit of a strange conduct by columbo to let the daughter off the hook.
However I saw a phrase which annoyed me: "I think we can all agree that Abigail would never hurt anyone else, and she had a much more sympathetic motive."
This much more sympathetic motive for abigail was revenge! Abigail is actually one of the murderers that make me happiest when they get caught.
I also hope this episode comes out on DVD asap.I am dying to see it. So far I have seen upto the first episode of season 9, i.e, "Murder, a self portarit".
The key to this episode, I think, is the tie that Lauren buys for him. All the time Lauren is trying to get on the good side of Columbo in order to throw him off the track, or maybe to persuade him to drop the case and let her off. But you know the Lieutenant, he can't be corrupted in that way. Many other muderers have tried similar tricks... flattery, lavishing expensive cigars on him etc etc, but they never succeed.
At the very end of this episode, Columbo gives the tie away and makes a statement about Mrs. Columbo that makes you realise he is totally professional, incorruptible and would never be unfaithful to his wife. This is the point when you get the impression that Columbo was just playing along with Lauren's amorous tricks and never intended to let her off the hook. Justice was seen to be done, even though Lisa escaped without charges... but in any case there was not really enough evidence to convict her.
I don't think Columbo fell for Lauren... I think he was just playing along all the time.