Why trust the injured man? Maybe he is not telling the trues. If investigations can not find the murderer(s), this file remains unsolved and nobody should be punished without having evidence.

Do not trust! Verify!

Some sort of prisoners dilemma: separate each of the 4 and offer leniency to the first one that admits guilty and turns the other two accomplices over. Hang the 2 guilty, release the innocent with compensation for the misunderstanding, and let the rat live out their days working for the betterment of the kingdom.

You are the king of a city. One day a very injured man appears, and before he dies he tells the guilty: 3 shoemakers killed me, and dies.

There are 4 shoemakers in the city and investigations cannot separate the innocent one.

What do you do and why?