Police said there were no suspicious circumstances in the death of the 52-year-old on the Thai resort island of Koh Samui on Friday.
Citing autopsy results, Thai Police Lieutenant-General Surachate Hakparn, assistant commissioner-general, told a news conference on Monday that Warne's death was due to natural causes, with no signs of foul play.
Songyot Chayaninporamet, deputy director of Samui Hospital, told reporters the autopsy report showed Warne died of a "congenital disease".
"There is no COVID-19 infection and no sign of assault or murder," Songyot added.
Warne's body was to be transported to Bangkok on Monday night and flown back to Australia on Tuesday, media reports said.
In a statement on Monday night the Warne family said the night of March 4 was for them the beginning of "a never-ending nightmare", and the cricket icon's death was "a tragedy we will never come to terms with".
"Looking to a future without Shane is inconceivable, hopefully the mountain of happy memories we all have will help us cope with our ongoing grief," his father and mother Keith and Brigitte said.
Warne's son Jackson wrote: "To my brother, my best friend, to my Dad, I love you so much. I don't think anything is ever going to fill the void you have left in my heart."
Warne's youngest daughter Summer wrote: "Dad, I miss you so much already. I wish I could've hugged you tighter in what I didn't know were my final moments with you. And your final breaths were only moments away."
Eldest daughter Brooke wrote: "I am lucky and will forever be so proud to call you my Dad forever. I love you to infinity and back and I will miss you forever."
More details have been revealed about the Melbourne-born cricket legend's passing.
One of the paramedics called to the scene on Friday after Warne was found unconscious in his villa has described how his friends desperately tried to revive him by applying CPR.
"They were desperate. I think one was crying. They were really stressed and panicked," Anuch Han-iam told British tabloid The Sun.
"They kept trying to wake him and I heard someone saying, 'come on, Shane, come on, Shane'.
"I could see they were all shocked and I just tried to concentrate and do my best.
"I did my best for him and gave all my energy. I'm so sorry that I couldn't help him," Anuch said.
Bo Phut Police Station Superintendent Yuttana Sirisombat earlier told reporters on Koh Samui island that Warne had been suffering chest pains before arriving in Thailand. He also had asthma and had seen a doctor about his heart.
Warne's manager James Erskine has also revealed the cricketer had recently come off a "ridiculous" fluid-only diet.
"He did go on these ridiculous sorts of diets, and he was just finished with one," he told Nine Network on the weekend.
"It was a bit all or nothing. It was either white buns with butter and lasagna stuffed in the middle or he would be having black and green juices.
"He obviously smoked most of his life. I don't know. I think it was just a massive heart attack."
Warne was only three days into a planned three-month holiday.
His friend Andrew Neophitou, who was among the group, had gone to check on him.
"They were going to have a drink ... or go and meet someone to go out and have a drink at 5pm and Neo knocked on his door at 5.15pm because Warnie is always on time," Mr Erskine said.
"He went in there ... and then realised something was wrong. And he turned him over and gave him CPR and mouth-to-mouth, which lasted about 20 minutes and then the ambulance came."
Victorian Premier Daniel Andrews confirmed on Sunday Warne's family had accepted the government's offer of a state funeral.
"It will be an opportunity for Victorians to pay tribute to his contribution to his sport, to our state and the country," Mr Andrews said.
with Reuters
