Factual error: An important plot point is that diamonds do not burn and can be recovered from the ashes of a cremated body. This is completely wrong - diamonds would combust freely at cremation temperatures, and since they are pure carbon they don't even leave any residue.
Factual error: In common with many other episodes neither Columbo, the attending police officers or forensic investigators wear gloves or other sterile gear while examining the murder victim's body or the crime scene. Columbo hands out bananas to other people on the scene which they happily eat. The senior crime scene forensics officer, Kingsley, hands out coffee and doughnuts! Eating and drinking are absolutely forbidden on a sterile crime scene, which has been hopelessly contaminated with fingerprints anyway.
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.
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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."
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