Who is The Mestizo Man from The Power and the Glory and what is their importance?

The Mestizo man is also referred to as 'half-caste.' The priest first encounters him laying in a hammock on his way to Carmen. The man has only two teeth that look like yellow fangs. He immediately suspects that the priest is in fact the wanted priest. Right away the priest suspects that the man will turn him in for the reward money. The priest tries to escape from the man but he keeps turning up.