The two sharks involved were initially a bronze whaler and then a white pointer, said Mr Jago.
He said Mr Strange had phoned lifeguards at 12.36pm to say he intended to make a training swim a couple of times from Maori Bay to Muriwai's main beach.
Lifeguards saw him complete the first swim, then walk back along the track to Maori Bay.
At 1.15pm Mr Strange entered the water, Mr Jago said. "Almost immediately Adam was subjected to the first of two shark attacks by what we now know to have been a bronze whaler shark.
"It is apparent that Adam unwittingly swam into one or more sharks feeding in shallow waters close to shore.
"Within a very short space of time - 90 seconds - Adam was subjected to a second and fatal shark attack; this time by a white pointer.''
Mr Jago said from the extent of Mr Stranger's injuries, his death was almost instant.
The white pointer then carried Mr Strange's body 300 to 400 metres towards the main beach.
Two lifeguards attempted a rescue, driving an inflatable boat into the white pointer and clubbing it with a paddle.
The pair realised Mr Strange was dead and decided it was too dangerous for them to remain because there were other sharks in the area.
Soon afterwards two more rescue craft were deployed and police fired 12 shots at the shark, as it was still "harassing the body''.
Mr Jago said an analysis of video footage by emergency services gave him confidence the shark had been killed by the gunfire.
He said he understood there were a number of unique characteristics which had driven interest in the incident. "Firstly the event was witnessed from start to finish. Secondly there has been a response to try and save Adam, something that's not often possible in shark attacks. Moreover we have Adam back, and that is not often the outcome in such events.
"Thirdly, there has only been one previously documented situation where a white pointer shark has operated in conjunction with a bronze whaler to attack a human.''
Victim mourned
The service for shark attack victim Adam Strange was held today at Muriwai Surf Club.
Hundreds of jandal-clad mourners gathered for the farewell, some carrying flowers, other food.
Many young people from the tight-knit community brought their surfboards which were used in a guard of honour as the coffin was carried in.
A club spokesman said the funeral cortege had stopped at Maori Bay, where the family man died, en route to the service.
The father-of-one arrived in an open-top combi van taking him to loved ones.
The call of a karanga and a conch could be heard as the coffin made its way into the building.
A surfboard was carried aloft immediately behind by mourners.
The service was private.
