That's a great question, and it's a lot harder than it sounds (much like Lt. Columbo himself). The problem is that it took writer/creators Richard Levinson and William Link three tries before they got someone to buy the show about a disheveled, scatterbrained but otherwise brilliant police detective.

The long-running series premiered Sept. 15, 1971, on NBC. Prior to that, though, NBC aired two different pilot episodes -- both as two-hour telefilms -- to test the show out and gauge interest. But even these came after the character's real debut, in an installment of an otherwise forgotten anthology show more than a decade earlier.

The first pilot movie, "Prescription: Murder," aired three years before the show, and featured B-movie great Gene Barry ("War of the Worlds," 1953) as the villain -- a psychiatrist who tries to manipulate a female patient into helping him kill his wife.

The second pilot movie, titled "Ransom for a Dead Man," aired in March 1971. This one did the trick, as NBC finally picked it up to series.

I say "finally" because the journey started so much earlier. The character first appeared on TV in an episode of the short-lived anthology series "The Chevy Mystery Show," also on NBC, all the way back in 1960. The episode, titled "Enough Rope," starred longtime bit player Bert Freed as the famously forgetful sleuth.

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