I think I'd choose Candidate for Crime for the reasons you've given. In addition, this episode is brimming with topical issues Columbo writers liked to address (Watergate was hitting the front pages at this time).
All these picks are terrific....they really are...but I guess we could pick any one of the episodes and find so much "Columboism" in it. Negative Reaction is an excellent one....with Dick VanDyke......(I only mention that one so I can type in the "dyke" part and get away with it!!! )......but really..that episode is a true classic Columbo from beginning to end...as Galesko gets more evil-tempered and annoyed at Columbo.....
Yipes -- I certainly meant no homophobia (that censor filter really is picky -- I'm happy the estimable comedian's first name survived the cut).
I actually was asked years ago by a friend to teach a community college course on mystery films. It fell through, but you should have seen the selection I had ready for those kids.
Well..Martin...you aren't going to leave us in the dark here, are you??? What were your selections? Was it Negative Reaction as you said above...or were there others?
And I think mat also pointed that out about Dick VanDyke....you can say his first name but not his last.