The minister, the doctor, and the plumber

RAY: An off-duty policeman is working as a night watchman in an office building. He's doing his rounds, and he comes to a closed door. Behind the door, he hears voices. He hears people talking and an argument seems to be taking place. The voices are raised. He hears one of them say, "No, Frank, no! Don't do it, you'll regret it."

Bang! Bang! Bang! He bursts through the door. What does he see? A dead man on the floor.

TOM: And the proverbial smoking gun.

RAY: In the room, are three living people: a minister, a doctor, and a plumber.

He walks over to the minister and says, "You're under arrest. You have the right to remain silent..." and I don't remember the rest of it.

How does he know that it was the minister that pulled the trigger?

TOM: It was a convention and they were wearing nametags?

RAY: " Hi, my name is Frank, and I'm armed!"

TOM: "And I'm the guy who just shot…"

Think you know? Drop Ray a note!

[ Car Talk Puzzler ]