Puzzler of the week

[Scott MacLean]

This week's puzzler:

An off-duty policeman is working as a night watchman in an office building.

As he's doing his rounds, he comes to a closed door. Behind the door, he hears people talking and an argument seems to be taking place. He hears one of them say, "No, Frank! No! Don't do it, you'll regret it!"

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

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..."

Here's the question: How does he know that it was the minister that pulled the trigger?

Last week's puzzler:

All of us remember from our high school or junior high school physics, that the Moon has a fraction of the Earth's gravity. In fact, we were all told that it's a sixth the gravity of the Earth.

For example, if you had a bathroom scale, and you put your 600-pound Bengal tiger on this bathroom scale, and then transport the tiger and the bathroom scale to the Moon, the Bengal tiger would weigh 100 pounds.

Here's the question. Is there anything you can think of that, if measured in the same way, would weigh more on the Moon than it does on the Earth? Now, I have an answer in mind, but there may be more than one right answer.

Last week's puzzler answer:

The answer is a helium balloon. Any balloon with lighter-than-air gas, such as helium or hydrogen, would work for an answer. Because on the Earth it wouldn't weigh anything on the scale. If you tried to put it on the scale it wouldn't register because it would float away. But on the moon, because there is no atmosphere, in addition to being not much gravity, there's nothing for the balloon to float on. Therefore, if it doesn't explode, it'll sit on the scale and it'll actually weigh something, whereas on the earth it doesn't weigh anything.