Ted, that is brilliant. I never thought of that psychology element before. Always finding the mechanics of the final clue of "Any Old Port in a Storm" to be somewhat confusing, the psychologically motivated explanation adds very uplifting insight.

Ted,

You have given me the answer I needed. I remember the Poe reference but it just didn't click. Now it does. Many thanks to you.

I think with some episodes, and this one in particular, you have to allow for 'poetic license' in the plot. For example, if the wine cellar was air tight how did it get so hot just because the outside temperature was hot? It presumably is some ways underground. The ground temperature wouldn't fluctuate very much due to a single hot day, and with no air exchange where did the heat come from?

this has been bugging me too, but it seems that you got lots of good info from other folks :)

You are right on the mark here. I've worried over this and come up with an hypothesis or two. First, Carsini cut off the air to suffocate his brother. Second, he did it to control the temperature of the corpse, a theme in many an episode. Since Carsini threw the body in the (understandably cold)ocean, temperature control was meaningless, so then he was trying to suffocate his brother. That would look like the brother lost oxygen during his dive. If you look at the wine cellar, you might notice that the volume of air inside would more than sustain an unconscious and unmoving person. Columbo, because of time constraints, uses a kind of shorthand for murders. The victim is in a sealed room, he suffocates. The victim is shot, the bullet went through his heart. The victim is poisoned, it was phenobarbital.
So, Carsini's brother was left in a very large cave, and he suffocated in a huge volume of air. The underground wine storage room, originally designed to control temperatures prior to modern air conditioning, being impervious to temperature changes, would not allow the wines to be corrupted in the short time allowed in this episode.

In watching Columbo, we cannot be less observent than he is. As fans, we are our own Columbos, and Columbo is our main suspect.

I love that!