INVESTIGATORS found no reason to suspect foul play in the death of abalone diver Peter Clarkson.
An inquest into Mr Clarkson's death began at the Port Lincoln Magistrates Court on Monday.
Mr Clarkson had been diving for abalone near Perforated Island when he was attacked by a shark while diving with skipper Howard Rodd on February 17, 2011.
SAPOL investigating officer detective Brevet Sergeant Anthony Boots said investigators had concluded there was no reason to suspect any foul play had been involved in the incident.
Detective Boots was the first to give evidence in the inquiry into Mr Clarkson's death.
He said on the afternoon Mr Clarkson was attacked, he and Mr Rodd had arrived at a dive spot near Perforated Island referred to as The Lumps.
Mr Clarkson was underwater for about 10 minutes when Mr Rodd heard the compressor change, which often indicated a bag of abalone was about to be floated to the surface.
Mr Rodd roughly pinpointed where he thought the abalone bag would hit the surface about 100 metres ahead of the boat and began to steer the boat over towards where he could see air bubbles breaking the surface.
Mr Clarkson then breached the surface and was described as looking "disabled".
"(Mr Rodd) then noticed blood around the water," Detective Boots said.
Mr Clarkson had blood coming from his mouth and Mr Rodd then observed a shark grab him around the waist and drag him underwater.
Detective Boots said Mr Rodd described this moment as the last time he saw Peter Clarkson.
Detective Boots said Mr Rodd circled the ocean looking for Mr Clarkson but was not able to recover him or any of his dive equipment.
Despite having various systems in place on the boat such as an Emergency Position Indicating Radio Beacon (EPIRB), he said Mr Rodd returned to the boat launch at Point Avoid in the Coffin Bay National Park about three hours after the attack and made several phone calls but none of them were to emergency services.
Detective Boots said Mr Rodd contacted Western Abalone Processors manager Jim George, friend Michael Coates and his son Neil Rodd before calling his accountant.
Mr George and Mr Coates then travelled to the boat launch to meet Mr Rodd with Mr Rodd's son Neil and other men from the oyster industry.
The group then proceeded to load the boat onto a boat trailer and return to Port Lincoln so Mr Rodd could receive medical treatment, and the group left the scene as ambulances arrived.
Detective Boots said emergency services were the last to be notified of the incident and police first attended the scene at Point Avoid at about 8pm.
He said police seized the boat at that point and it was taken back to police lockup.
Detective Boots said when the boat was examined by forensics, three drops of blood were found near the roof of the cabin on the abalone boat.
He said one of the droplets of blood matched Mr Clarkson's DNA profile.
A part of the compressor hose that Mr Clarkson was using on his dive, which was also found on Mr Rodd's boat, was also tested by forensic officers to see if it was consistent with a shark bite.
After investigators found the damage to be inconclusive, more tests were done where investigators had sharks attack pieces of hose and then matched them to the hose found on Mr Rodd's boat.
After matching the hose samples, investigators found the damage on the hose used by Mr Clarkson was consistent with damage made by a shark.
Detective Boots concluded Mr Clarkson was bitten by a shark while underneath the surface of the water and then dragged under the surface.
He said investigators found no reason to suspect any foul play had occurred in Mr Clarkson's death.
Mr Clarkson's brother and sister were in the courtroom during the inquest on Monday.
The inquest is expected to continue until Friday with 11 witnesses scheduled to appear, including Howard Rodd, who was the skipper on the abalone boat the day Mr Clarkson died.
Others to give evidence will be Western Abalone Processors manager Jim George, Abalone Industry Association of SA executive officer Samara Miller and abalone divers Darryl Carrison and Paul Claughton.