I'm sure if we brainstorm we can come up with a lot. But one comes to mind for me. Joe Devlin. Trying to convince Lieutenant Columbo that he is now a detective and actually at the Los Angeles Pier number 13. LAP 213. I mean come on now does he actually expect the lieutenant to all of a sudden think that he is now a detective? And working on this particular case? How stupid can Joe be.

ok your turn guys!!! let come up with a good list of dumb moments.

Did you watch a different version than me??????

Off the top of my head, I'd say that Hayden Danzinger (TROUBLED WATERS) was the stupidest murderer. Why would he admit to planting the gloves?

A close second would go to DOCTOR Bart Kepple (DOUBLE EXPOSURE), who after going to all the effort to concoct an alibi for the shooting of Vic Norris, leaves the only real direct evidence to the crime in his office lamp! He had all the time in the world to dispose of the calibration converter, but never did.

How about Beth Chadwick trying to convince Columbo that the servants cleaned a burnt-out bulb. To think that he would believe that is absolutely asinine

It's a little smaller than the one John mentions, but why does Hayden not bring gloves along in the first place? Maybe he's never committed a murder before, but that be should about the first thing that occurs to someone planning one, whether they have or not.

In the Danzinger stateroom at the beginning of the episode, Hayden says, "Sylvia, do you know where my golf gloves are?" She replies, "Oh, I guess (Johnson) forgot to pack them."

His "peevish" reply earns him a chiding from his less than omnipresent wife (whose non-appearance at the hospital room and relative non-appearance throughout the rest of the episode has always bothered me) and his reliance on the butler to do his packing reveals his utterly spoiled little boy nature, which ultimately leads to his capture. If he hadn't been such a whiny little baby and packed his own gloves for crying out loud, he might have gotten away with the crime!

Paul Galesko IMO had two stupid moments.

1-Not retrieving the discarded photo of his wife even though it was in plain sight and a smart killer would have picked it up right away.

2-If Galesko is trying to make Columbo think a simple-minded ex-con committed the crime he would NOT go out of his way to volunteer so much to Columbo about how the discarded picture is a bad picture in ways that only a professional photographer would know or understand. He's just calling attention to the fact that someone like Deschler couldn't possibly be that sophisticated.

In Caution, Murder can be hazardous, the whole business with Wade Anders replacing the cigarettes was stupid. There was no need to do it, or leave a lot cigarette in the victims hand.

I've always thought the stupidest thing a killer ever did happened in Mind Over Mayhem when Dr. Cahill stopped in the middle of staging a crime scene to light a cigar and then throw the match in a clean ashtray.

What about Brimmer in Death Lends a Hand telling Columbo he was ambidextrous and writing with his left hand AFTER Columbo told him the murderer was left-handed? Keep your mouth shut and act like a righty in Columbo’s presence.

Actually, Brimmer's goof was writing with his left-hand after the matter of the killer being left-handed was established which prompted Columbo to notice, "Isn't that something! Here we were talking about the killer being left-handed and you're left-handed!" Then Brimmer switches to his right hand and mentions being ambidextrous. So Brimmer's goof was signing left-handed initially whereas if he had signed right-handed, Columbo never would have spotted the "coincidence".

Yes, that’s right.

Viveca Scott in Lovely but Lethal. Why does she need write those figures on that magazine? OK the murder was not premeditated but why does need to write them down?!

Also Paul Galesko, stupidly writing down the ransom amount but not the address. It makes logical sense to write the address but then he leaves the note behind anyway. Another silly thing to do.

Starting the Tchaikovsky LP in the middle.....