E has inspired me to try this.........hopefully I won't screw it up, as I have had in the past.
What links these episodes together? Something DOESN'T happen in these eps that happens in the others.
Murder By The Book
Death Lends A Hand
Dead Weight
Suitable for Framing
Lady In Waiting
Short Fuse
Blueprint For Murder
Etude In Black (yay! )
The Greenhouse Jungle
The Most Crucial Game
Dagger Of The Mind
A Stitch In Crime
The Most Dangerous Match
Double Shock
Lovely But Lethal
Any Old Port In A Storm
Candidate For Crime
Double Exposure
Publish Or Perish
Mind Over Mayhem
An Excercise In Fatality
By Dawn's Early Light
Troubled Waters
Playback
A Case of Immunity
Identity Crisis
A Matter Of Honor
Now You See Him
Last Salute To The Commodore
Fade In To Murder
Old Fashioned Murder
The Bye-Bye Sky .............yada yada
Try And Catch Me
Murder Under Glass
Make Me A Perfect Murder

and a few honorable mentions..for when it may have happened....
Requiem For A Falling Star
How To Dial A Murder

and in a different way..
A Deadly State Of Mind.

ok..........I just realized that I should have listed the ones that included this thingy I am referring to.......it would have been a much shorter list!!!

i have no clue but im really interested to know the answer!!!

there are clues in there sabra......

Does it have something to do with spouses? I was thinking about some things, but I'm not yet sure how it might all fit together. Should I keep thinking in the spouse direction?

Oh heck.......don't struggle anymore.....you got it.
All those I listed did not have a murderer killing their spouse.
In Requiem and How To Dial A Murder, they probably both killed off their spouses...but that is not the case that Columbo is working on.
And in A Deadly State Of Mind a spouse is killed while the wife is there, but it is Collier who strikes the fatal blow.
As I said, I should have listed the episodes where the spouse is killed instead of the other way around!! The list would have been a heck of a lot easier to type!!
Great Job E!!!