That's right. He was the missing person in the kitchen after we found the cook dead.
4 seconds sound clip from the Clue (1985) movie soundboard.
You can hear this line at 01:28:43.185 in the Blu-ray version of the movie.
Quote context
[...]
- Sorry, didn't mean to frighten anyone.
- Then there were three more murders.
- Let's consider each murder one by one.
- Professor Plum. You knew Mr. Boddy was still alive.
- Even psychiatrists can tell the difference between patients who are alive or dead.
- That's right. He was the missing person in the kitchen after we found the cook dead.
- But he was with us in the billiard room when we found Yvette screaming.
- If that's when the cook was killed, how did he do it?
- You don't expect us to believe that, do you?
[...]