In Murder Under Glass Columbo conducts a conversation with a witness in Italian. On the Columbo Quiz portion of this website it states that Columbo spoke more than two languages. But, if I remember correctly, in Strange Bedfellows when the Rod Steiger character speaks Italian to Columbo the Lt. claims he doesn't speak the language. Did he forget? Maybe he was playing dumb to keep his distance from a person that he didn't like, but needed to nail the killer?
Are Italian and Sicilian different languages or are they basically the same? I assume that a person that speaks one would understand the other.
Agree with Cassa'. Columbo shows a certain insolence (excellent acting here) when he tells Steiger that he doesn't speak Italian.
As I see it, Steiger's character is attempting to draw Columbo into a little web of solidarity, by invoking their common language. And when Columbo responds by pretending that he does not speak Italian, he is intentionally lying to the mafioso's face -- note how Columbo glares at him -- as a way of telling him, "You are a criminal and I am a policeman -- so, I do NOT consider you my paisan!"
Steiger probably knows perfectly well that Columbo speaks Italian, which is why the insult stings.