The reason they went to the serial killer's camp was that they suspected the killer had imprisoned other victims and ended up ambushed by a female gunman, forcing them to retaliate for their own safety.
They had carefully studied this story and thought through some details, even going so far as to find a spot where they had discovered treasure.
Additionally, they had a treasure map, and their purpose for coming to Red Rock Canyon was to hunt for treasure, so obtaining it was a logical outcome.
With the two serial killers dead, and no testimony to refute, the treasure was dug up by them.
Given their identities, no one would insist on questioning this matter.
After arranging everything, they left Red Rock Canyon, with Walker driving the RV and Luke driving the pickup truck.
On their way, they passed by the place where the black woman had been killed.
