Catlow

POISON
They were traveling through the toughest desert in Mexico, a place of knife-sharp lava beds, rock-ribbed mountains, waterless canyons. And Catlow knew the dread Seri Indians were following them.
Pesquiera said, "We got to get to water." Catlow reckoned this man would quit He didn't care. It meant that much more gold for him.
When they saddled up in the morning, Pesquiera was gone.
But they found his body, less than a mile from camp, a poisoned arrow through his throat. His face, neck, and the upper part of his body had already turned black . ..
And they still had two hundred miles to go ...