Many criminals made the mistake of underestimating Lieutenant Columbo, a homicide investigator with a crumpled trench-coat and a beat-up car, who certainly acted as an incompetent bumbler.
But he was so polite to every suspect, and he talked so much about his wife (who we never got to see on any episode, but who many believe later had her own show, starring Kate Mulgrew, later of Star Trek: Voyager fame) that he lulled even the shrewdest murderer into a false sense of security.
And although the audience had witnessed the murder in the beginning of each episode, it was still a surprise to see what mistakes the killers had made during the seemingly perfect murder.
A health club owner kills his partner who is about to uncover a fraud and makes it look like an accident
Brilliant photographer Paul Galesko plans to murder his domineering wife, Frances,
and pin the crime on an ex-convict named Alvin Deschler. His plan is to make it look as if Alvin kidnapped his wife and killed her before picking up the ransom money.
The head of a military school kills one of the governors by sabotaging the gun which is used on Founder's Day.
While holidaying on board a cruise liner, Columbo helps capture the killer of the singer with the ship's band.
An inventor video tapes his mother-in-law's death, and then replays it back to the security guard, to give himself an alibi.
A doctor kills the husband of the woman,he is having an affair with. but is seen leaving the house by a witness who is happens to be blind.