My understanding is the four wheel drive was in a driveable condition. That's why it's likely foul play. Why wouldn't you evacuate by the car , even if one person was incapacitated or use the radio if available. Secondly whilst there are a few theories it's established as fact that the wife of the guy did not know that he was camping with that lady. Finally my mum knows this lady , very active in the community and salt of the earth type.