An investigation into the death of a scuba diver whose body was found with big bite marks may never reveal whether he died from a shark attack.
Michael "Mick" McGregor, 38, failed to resurface while diving with friends for rock lobster on Saturday afternoon about 5km off Dawesville cut in Mandurah.
Police divers found human remains believed to be his on Wednesday in an area near the dive site.
The coronial investigation unit have called in experts to help determine some circumstances surrounding the shark bites on the father of two's body.
_The West Australian _understands, however, that the shark researchers' main aim will be to try to determine what kind of shark attacked Mr McGregor, not whether the attack proved to be fatal.
It is understood Mr McGregor's significant injuries will make it too hard for investigators to determine whether he may have died before the suspected attack.
Department of Fisheries shark research scientists have previously assisted police investigating fatal shark attacks, including the deaths of Bryn Martin off Cottesloe and Brian Guest at Port Kennedy.
Teeth mark examinations often help determine the shark species involved.
Friends and family yesterday paid tribute to Mr McGregor's generous spirit.
Shane Wylie, who had been with Mr McGregor at the time of his disappearance, told Seven News his friend was "the best person he had ever met".
He described his anguish at having to wait on the surface after Mr McGregor vanished because all air tanks on the boat were empty.
"We didn't have any more tanks left," Mr Wylie said.
"We knew we were all on our last one, so we all just waited and watched hoping to see him.
"I can't really describe it. It's the worst feeling I've ever felt.
"It was just a routine dive. We were doing what we loved and something's gone wrong."
Police divers yesterday returned to the area where the body was found in the hope of finding any more clues.
None of Mr McGregor's diving equipment has been found and the search for any more gear is believed to have been called off indefinitely.