Adrian Monk: You see that dump truck over there?
Natalie: Yeah.
Adrian Monk: That's the one that passed us on the highway. Do you remember?
Natalie: Yeah, he wouldn't honk his horn. He must not be a very happy person.
Adrian Monk: The guy who was killed.
Natalie: Steve Marriot.
Adrian Monk: Marriot, right. I think he was already dead. There's no other explanation. Because his car never passed us. I think it was inside that dump truck. And then it got dumped out in the middle of the highway.
Natalie: By who?
Adrian Monk: By him. The paramedic who was treating you.
Natalie: What?
Adrian Monk: He's got mud on his boots that matches the mud on the tires of the Volkswagen. He's the guy.