Caldwell did pretend to be the real killer of the DA's wife- he publically dumped the body in the pool. So, my answer fits even if it's not what you had in mind.
LOL - forgot about that part.
Wild guesses. Dog is in both eps. COLUMBO takes a test or is supposed to take a test in both?
I didn't mean to quote you Bruce Marshall. I hit the quote button instead of the reply button.
The connection I was thinking of was that although in many episodes his car is often unreliable, in these two episodes it actually breaks down.