If not for the suspects confessing would most get off?
It seems the evidence Columbo gets is weak circumstantial evidence. I just watched Identity Crisis with Patrick McGoohan as the killer. Columbo’s main evidence of guilt was McGoohan saying on a tape, “The Chinese may pull out of the Olympics, but they’ll never leave soybeans.” Or something like that. But the Chinese pulled out of the Olympics a few hours later than what the suspect said was the time of the recording.
I find that so weak. If not for McGoohan admitting everything to Columbo after that confrontation, would he even be charged with murder.