Grant Hackett's family have reported the Olympic champion missing and appealed for the public to help find him.
His father Nev has told reporters on the Gold Coast the family does not know where his son is and says the three-time Olympic gold medallist needs help.
"He's definitely a missing person. He's mentally disturbed and needs urgent help ... If anybody has seen him contact the media or the police or the Hackett Family."
"Grant, let us know where you are. We love you and we want to help you."
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