Lauren Stanton had 0 remorse about killing Nick Franco. That two-timing rotten skunk. Lisa probably didn't have any guilt feelings either.
Kay Freestone shows no remorse when she's taken to the station. She even tells Columbo that she'll fight the charges against her and may even win that battle.
There's no sign at all that she regrets killing.
Paul Galesko had no remorse. He even killed poor Alvin Deschler to try and set him up as the killer.
I always wonder whether he has a different attitude about each of the two murders, and I always like to think he means it when he says, "I'm sorry, Al...."
There's Roger Stanford.
For one thing, there's the way he wastes no time moving into David's office, and isn't even a little sneaky about it.
In fact, with some of the way he acts he almost fits the pattern of the "criminal who wants to be caught" (though of course he isn't one of those).
None of the Jack Cassidy murderers (Franklin, Greenleaf, and Santini) seem to have any remorse at all!
Wesley Corman - the dentist. Had he successfully framed his wife she would have been committed to an institution and when questioned he justifies it by saying something like 'it was no worse than what you both had planned for me'.