It's possible that his intended victim was a man and he made a mistake.
4 seconds sound clip from the A Shot in the Dark (1964) movie soundboard.
You can hear this line at 01:26:17.168 in the Blu-ray version of the movie.
Quote context
[...]
- Nevertheless, it proves that my theory is correct.
- So jealous he made it look like Maria Gambrelli was the murderer?
- Was he jealous of her, too? He strangled her.
- It's possible that his intended victim was a man and he made a mistake.
- A mistake? In a nudist camp?
- Idiot!
- Sir.
- Lunatic!
- I will have your murderer for you by tonight.
- What?
- A plan that cannot possibly fail.
[...]