Susan Clark gives a fine performance as a male-dominated female who "bumps-off" her brother to protect her relationship with her boyfriend (Leslie Nielsen) and give her back her independence.
This story gathers intensity as the murderess (the first female killer in the actual TV series) is dismissive of any intrusion by others into her family business and she becomes more manipulative and insensitive as Columbo gets closer to the truth - an effective piece of scripting and a hallmark of the series in that Columbo invariably annoyed his chief suspect almost to the point of a nervous breakdown!
The ending is also significant since Columbo's life is clearly on the line. However, the effectiveness of the irony that the killer's boyfriend unwittingly gives Columbo the vital piece of incriminating information, is undone by the fact that the clue could easily have been pinpointed earlier.
This clearly gives the impression that the script-writer had some difficulty in providing a satisfactory conclusion to an originally well-thought-out concept.