A man found unresponsive near the Eyre Highway with a serious head injury following a robbery in January has died in hospital.
The 67-year-old was found in Bookabie, 100 km west of Ceduna, on 20 January, and died in hospital on 20 March.
On the same day, a 39-year-old Thevenard man and a 28-year-old Yalata woman were arrested and charged with robbery.
Both suspects were remanded in custody to reappear in Ceduna Magistrates Court on 1 May.
Police believe this was not a random incident, with all parties known to each other.
The incident has now been declared a major crime.
A file is being prepared for the Coroner and charges are being reassessed.