UPDATE: Grant Hackett has been found alive and well.
Police tracked the Olympian down on Wednesday, several hours after his family reported him missing.
He reportedly made contact with police and his parents to let them know he was safe.
EARLIER: Grant Hackett has gone missing after his arrest on the Gold Coast.
The Olympic swimming champion's family raised the alarm on Thursday.
His father Neville Hackett told Channel Nine his son hadn't been seen since leaving Palazzo Versace around 7:30am.
He begged police and the public for help in finding him.