Stupidity: Why does Jack Cassidy plant the lighter in the office when he could just pretend he has forgotten it? Does not make sense.
Factual error: Devlin proclaims himself to be a staunch Irish Republican but he refers to the Northern Irish city of Derry as "Londonderry." This is the name imposed upon the place by the British and is despised and rejected by Republicans. Devlin would refer to the city as "Derry."
Trivia: Columbo's first name is never mentioned throughout the series. However in a few episodes, such as "Dead Weight", "A Matter of Honor" and "Death Hits the Jackpot" he flashes his badge and the name "Frank" can clearly be seen.
Any Old Port in a Storm - S3-E2
Question: As a homicide detective, why would Columbo have been present at an apparent drowning incident?
Answer: "Apparent" drowning answers your question - things are not always as they seem. Drowning could be accidental, but it could also be a murder in disguise. Moreover, the actual cause of death has not yet been determined - accident, suicide, murder, or natural cause (e.g, heart attack while swimming). Columbo would be there to investigate if anything looks unusual for it to be a mere drowning or if there is evidence or suspicion of something else.
KeyZOid
This was just on TMZ.com's "Aaron Carter Dead at 34" (11/05/2022): "Law enforcement sources tell TMZ... homicide detectives have been dispatched to the scene but we have no information or evidence of foul play. It's standard operating procedure for homicide detectives to investigate such [drowning] death scenes."
KeyZOid