I have mixed feelings bout that too, though I'm glad that SOMETHING caused Janie to get arrested, because it led to that great scene in the cell, with the "ashtray." But it would be even better some other way, without the frame-up by Ruth. So like you, I have kind of a problem with that.
One strange little piece of trivia. Tim O'Connor appeared in two episodes this one and Double Shock and in both of those episodes at some point his character is doing an inventory of rare antiquities.
I just saw DOUBLE SHOCK again, and I noticed a further one, since they each have someone mistaking an art object for an ashtray. In OLD-FASHIONED MURDER it's Janie of course, and in DOUBLE SHOCK it's Columbo himself.
this is one of my least fave episodes....and full of "holes" as you describe Irene...plus the Celeste Holme character passing out is simply too over the top for me....
I do however like the "tone" of the episode and Joyce Van Patten plays the character with fine restraint...
I just watched this yesterday, and my two takewaways were "no gunshot residue on either victim's hands", and didn't make sense she would implicate the Neice, who she seemed to care for dearly, "like her own daughter" she said.