Dr. Collier: Am I to presume that I'm currently your chief suspect?
Columbo: I'm not sure suspect is a strong enough word.
Dr. Collier: In that case, I should be locked up. Of course, I'm not. Therefore, I presume you have no proof.
Columbo: Not yet.
Dr. Collier: You'll let me know when you do, won't you?
Columbo: You will be the first to know, Doctor.