The 49-year-old was last seen alive days earlier at a celebration with friends for the AFL grand final on Saturday, September 27.
Today SA Police found a grey Mitsubishi Triton concealed at a large property in Cherry Gardens in the Adelaide Hills.
They suspect the ute was used to take Robertson there, where he was beaten to death.
Police say the registered owner of the vehicle is not a suspect in the murder, but they believe someone else was driving the ute, who may be involved.
Anyone with information can contact Crime Stoppers on 1800 333 000.
