Though it's obviously the murderers' relationship to Columbo that is always the focal point of nearly every episode ("Last Salute To The Commodore" would be an exception) I find many of the victim/murderer relationships to be, in many instances, very intriguing as well. And in some of those cases, it's that vital confrontation between murderer and victim, where the murderer becomes intent on killing, that is most striking to me.
Of course, in several episodes the murderer has it all planned from the very beginning, although even in some of these cases there are moments where the tension comes to a head right before the murder is set in motion ("Candidate For Crime" and "Playback" among others). Then there are the "moment of passion" murders, where the breaking point confrontation essentially IS the murder.
As far as the cases where the confrontation comes before any murderous intent has already been established, my favorites are Elliot Markham and Bo Williamson in "Blueprint For Murder" (though I feel most of the performances in the episode are sort of hit-or-miss, I think Patrick O'Neal is great, especially with his cool, calculated demeanor set in contrast to Forrest Tucker's bombastic rage as Bo); Milo Janus and Gene Stafford in "An Exercise In Fatality" (I love Gene's taunting, over-confident nature, especially his "I'm gonna hook ya, Milo" line); and Ruth Lytton and Edward in "Old Fashioned Murder" (the pensive expression on Ruth's face as Edward lays out his uncompromising decision to close the museum sort of sums up for me the over-arcing story of her life; both her brother and sister constantly forcing through decisions for the family that had detrimental consequences for Ruth, while she was obliged to listen and accept them).
I really like the confrontations in several other episodes as well, such as "Mind Over Mayhem" and "Make Me A Perfect Murder".
Does anyone else have a favorite scene or scenes of this kind?

One I always notice is when Ric Carsini makes Adrian so mad that he gives Adrian that little pat on the cheek as if to calm him down. Adrian doesn't just make an angry sound at that, it's almost an "animal" sound!

Yes, Candidate for Crime is a great example of this. Candidate For Crime is for me the most unrealistic episode. But the acting is very good. One of the best scenes is in the beginning. We all know the scene in which Haywood returns from giving his speech at the police station. Haywood's campaign manager (who will be a victim in an hour or so) chides Haywood. It starts when they are together in the living room and the manager continues his harangue as Haywood gets his gun ready in another room. The manager is more than insulting and Haywood takes it, knowing he will kill his manager. His expressions are revealing. Great writing.

(As it turns out the manager is right. Haywood would not have gotten anywhere without his manager, as witnessed by Haywood's behavior in the rest of episode. The murder is sloppy and ill timed and possibly unnecessary. Haywood's reactions to Columbo show that he does not do well 'on his feet.' He uses a firecracker on the balcony. Harry Stone would have plotted a better murder.)

One thing about Ric and Adrian's confrontation that I've wondered about for a long time is if the distance of the office from the tasting room would have really been great enough for the arguing to have been unheard by Adrian's friends. As you alluded to, Grant, that confrontation got quite dramatic, and it seems as though at least some portion of it would have been perhaps slightly audible in the tasting room.
At any rate, I do love that scene, particularly in that both Adrian and Ric are completely selfish, hedonistic snobs, battling it out to protect the continuation of their respective indulgences, which is an amusing dynamic.

I agree, Ed, about the writing in that scene from "Candidate". I especially like Harry's grandly arrogant, derisive line, "Humility, Nelson. Humility. If I could do your thinking as well as your talking...etc." The whole episode is wonderfully written, which shows that a long list of script credits doesn't necessarily dilute an episode's quality.
Also, that's a good point about Nelson really not being able to function without Harry. It reminds me somewhat of "Lady In Waiting", where Beth shows her inability to manage the freedom she acquired through murder (not that I think Bryce's belittling of her was justified, though).

I watched By Dawn's Early Light the other day and it struck me for the first time how strange some of the nuances in it are from the more common types of murder, investigation and confrontation in Columbo.

McGoohan's character realises he has made a big mistake immediately once he hesitates to identify the rag. For the rest of the film he does not go out of his way to assist Columbo, but neither does he resist questioning too much or equivocate the facts. It's like he is careful not to make the same mistake twice or make excacerbate any problems caused by his first mistake. Once he realises that Columbo is on precisely the right line about the cause of death I believe he genuinely feels remorse at implicating Springer in a murder when he had only intended to charge him with negligence and have him drummed out.

At the point where Columbo is satisfied that the cadet is not actually involved in the case whatsoever, and at which point you'd expect there to be the first confrontation of sorts between Columbo and the killer, Rumford becomes whistful, knowing that he cannot prevent Columbo from getting to the truth, not that he trully wishes to at that point.

There are other scenes in Columbo where the killer goes into a sort of bargaining phase or tries to evoke some sympathy. Columbo is normally quite engaged at these points, exploiting the character's sudden expansiveness or reminds them that he intends to do his duty, whatever the circumstances are.

In this case though, Columbo just seems to switch off. It's as if he realises that he does not require to do the dance with Rumford so he allows the valediction but does not really respond to it whatsoever, either to reject it or to condescend. There an almost embarassed disinterest on Columbo's face. And by that I mean genuine embarassment that he's trying to hide, not the "gee whiz" schtick that he normally lays on the murderer.

I love the office scene between Santini...(Stefan Mueller) and Jesse Jerome....the reveal of Santini s identity
Nehemiah Persoff is excellent in this scene capping it off with the wiping of his brow....
Great tension there
and to me the BEST motive of any episode....sent to an Israeli prison camp etc...
There are a few cringe worthy moments too....like Columbo stating he saw Santini at Madison Square Gardens....just a tad of a stretch there and the fact that there are more people in kitchen than club itself...lol

The scene between Viveca Scott and Karl Lessing is "one long" breaking point. Instead of just refusing to bargain with her, he has to provoke her in all sorts of ways.

I love the scene between Bertie and Oliver in the Bye Bye Sky High episode. There's a moment in the confrontation between the two, right after Oliver has finished chiding and tickling Bertie that Bertie calms down and almost seems as if he is about to forgive his friend. But then, Oliver just can't help himself and returns to tickling and grabbing at Bertie. Bertie realizes at this moment that Oliver will never change and that he will always be the subject of his bullying and his jokes. It confirms in his mind that he is going to end Oliver's embezzlement activities and bring an end to his years of torment. You are left with the feeling that if only Oliver would have stopped and took a look at what he was doing, Bertie would have calmed down and they would have worked something out. It's a wonderful moment and a wonderful scene.

I love the final scenes in this episode as well. The moment where Oliver tells his wife that he no longer needs her takes some of the edge of of his bullying and overbearing character and adds a touch of humanity.

Even though he's already planning the murder, the obvious one between Hayden Danziger and Rosanna Wells is when he hits her, something a blackmail victim should never do to the blackmailer unless they're all set on murdering them right then and there!

I do have one big problem with that scene, and it's about the Rosanna line that actually causes it to happen. She simply tells him a little sarcastically to "be sensible." But a minute earlier when he says that "No two-bit singer" (or something like that) is going to jeopardize his business, she smiles and says "This one is."
It seems like THAT would be the line that makes him loses his cool, instead of the other one.

One thing about the Bye Bye Sky High scene is that Oliver professes to have really loved Bertie, so you would think he would have been a bit more kind to Bertie considering that it would be his last moments alive.

One thing that always seemed odd about Oliver's preparation for the murder is that when he is setting up the umbrella upstairs prior to the murder, he is almost giddy, presumably with how clever his set up is. However, I find it hard to fathom that anyone who is about to murder their closest friend, or even the fact that they are about to cross the line into an unthinkable act no matter who the victim, would not be giddy - they would be nervous, contemplative, distressed, but not giddy.