Oral evidence will prove crucial in the inquest into the deaths of two men who suffered strokes and died in the Royal Adelaide Hospital at a time when two clot-busting stroke specialists were on leave.
Coroner Mark Johns told a directions hearing on Monday that he had hoped the written material to be provided to his inquiry might offer a clear picture of the issues involved.
But he said it now appeared oral evidence was "going to be more the source of the story".
Mr Johns is inquiring into the deaths of 60-year-old Michael John Russell and 87-year-old Leslie Robert Graham and will start taking evidence in August.
He has also asked that the 14 witnesses scheduled to be called provide statements to the court in advance.
The coroner was previously told that health authorities had failed to act on a recommendation to hire a third stroke specialist at the RAH to perform the delicate clot-removal procedure.
A review of the neuro-interventional radiology service had called for the third specialist to be employed in 2013, four years before Mr Russell and Mr Morgan died in April this year.
Mr Graham was admitted to the RAH on April 18 after suffering a stroke at home.
He was assessed as a suitable candidate for the clot retrieval procedure but one specialist was overseas and the other on a fishing trip, south of Adelaide.
A similarly qualified specialist was called in from the Flinders Medical Centre to perform the procedure but it proved unsuccessful.
Mr Russell was admitted to the hospital the same day suffering from a heart attack but had a stroke while undergoing a procedure to clear a blocked artery.
He was also worked on by the visiting specialist, who had been called back, but again the procedure proved unsuccessful.
