When he first went missing, Marshall's immediate concern was for the dog's ability to survive, knowing he would need an injection in a couple of weeks. He rallied around the local community for help to find Gonker.
While he plastered the neighbourhood with flyers and returned to the hiking trail on several occasions, his mother set up a command centre in her home. Using a detailed map she set about calling animal hospitals, police stations and newspapers.
Local media picked up on the story and the family began getting tip offs from people.
One man made an anonymous call to Marshall's mother to ask if they had found the dog. When she told him they were still searching he told her they would never find him and promptly hung up the phone.
By day 13, Marshall was desperate, resorting to calling Gonker's name out into the darkness.
Fifteen days after he first went missing, Marshall's mother received a call from a police officer reporting a sighting of Gonker.
He had travelled 178 kilometres, covering at least 11km a day trying to get home.
Marshall drove to the area and was reunited with his beloved pooch. While the dog's paws were gashed from running over rough terrain, he had gained weight during his journey.
Gonker survived another five years and died at the age of 11.
Marshall now lives in Chile with his wife, two children and a new dog.