The doctor of Jonah Lomu has said that a blood clot is the most likely cause of his death.
Dr John Mayhew believes that the blood clot could have been sustained while Lomu flew from England to New Zealand after watching his country's Rugby World Cup victory.
"I think it was instantaneous. He was unaware of what had happened," Mayhew told BBC Sport.
"It's just one of those tragic complications that can occur in people with chronic renal conditions.
"He returned from the UK via Dubai and appeared to be in good health before he died."
Lomu will be remembered at a memorial service at the Eden Park Stadium on November 30.