Lieutenant Disher: Mr. Philby, you're under arrest for murder in the first degree, special circumstances.
Derek Philby: [scoffs] Come on. That's insane. I told you. I was...
Adrian Monk: Proctoring the S.A.T.s at the time. We know. It took me forever to figure out how you pulled it off. But then it hit me. You killed Beth Landow before the test started. You met her on the clock tower roof that morning at about 8:00, twenty minutes before the test. Then you killed her, and you carried her body down the stairs to the clock room. This was inspired. She fell, all right, but not from the roof. She fell from the clock. You laid her body out on the minute hand. It was 8:15, so the hand was perfectly horizontal. The S.A.T.s were to begin at 8:20. You had five minutes to get back to the classroom. Plenty of time. And you let gravity do the rest. It was just like one of your science experiments.
Captain Stottlemeyer: You took a pretty big risk, Philby, hiding the body in plain sight.
Adrian Monk: It wasn't such a bad bet. That side of the tower faced the athletic field, which on a Saturday morning was completely deserted. Tick tock, until 8:25, when the body slid off the clock and landed on your car. You made sure that the alarm was activated so that everyone would know exactly when she fell. It was a perfect alibi. There was only one problem. The groundskeeper just happened to see you.
Sharona: But you took care of him later.
Derek Philby: I told you, Mr. Monk, a theory is just that unless you have some proof.
Adrian Monk: It's true. I don't have any proof. But you do. It's in your hand.
Derek Philby: Oh! You see, l I found these on the roof. I think they're Beth Landow's. I think you're looking for them.
Adrian Monk: You didn't find them on the roof. You found them in the clock room under the gearbox, because I put them there two hours ago. Only Beth Landow's killer would have known to look for them there. QED. Quod erat demonstrandum. "Thus it is proved".