Stories with holes help, please!

[aisforamy]

My son's class is trying to solve a riddle that their teacher gave them, and they are having trouble with this one. My son thought my friends might have ideas about how to solve this mystery!

Some criminals put two night watchmen unbound and unharmed into the trunk of a car and locked them in. The next day, workers hear sounds coming from the trunk and open it. One man steps out alive and well, the other is dead. What happened to the night watchmen?

Any one care to give us some ideas?