Maybe to spare the lives of innocent people Columbo should have been put on traffic duty and left there. Columbo's method of investigation has caused a few murders over the years, there would be people still alive today if not for Colombo's irresponsible handling of suspects.

Dr. Mayfield murdered a nurse with a tire iron to cover up his plan to kill another doctor. Once Columbo identified Mayfield as the murderer and knowing he was capable of anything, he still continues to taunt him, badger him and let him in on every step of his discoveries. Columbo should have known someone like this would kill anyone to save himself. He should have kept the clues to himself without alerting Mayfield to every step of suspicion, all this did was cause Mayfiedld to kill another innocent person. It's lucky he didn't kill Marsha as well.

Same with Riley Greenleaf and Allen Mallory, and there are others....It's a shame Columbo was allowed to recklessly taunt dangerous people, goading them into killing again, someone should have put a stop to it.

Don't forget Mayfield also murdered Harry Alexander to frame him as well,in A Stitch in Crime.