Guma Aguiar was spiraling out of control before vanishing at sea

Last sighting: On this time-stamped CCTV footage, Mr Aguiar can be seen leaving his home in Fort Lauderdale, Florida

FORT LAUDERDALE, Fla. - Friends of a missing oil tycoon said Monday he'd been spiraling out of control for years, and seemed troubled and confused shortly before he disappeared as he sought treatment for severe bipolar disorder.

New surveillance video from a South Florida port shows 35-year-old Guma Aguiar steering his boat into rough seas less than half an hour after leaving his home. It is the last known image of the man whose boat washed ashore last week without him.

"I just stare at those pictures of him on that boat and can't help but be struck by the symbolism of him on a vessel by himself in rocky seas, fighting a world that he probably felt like was crashing down on him," said Wes Shelton, a close family friend who said Aguiar was troubled in the months before his disappearance.