06/22/2012 10:35 am ET Updated Aug 22, 2012

Guma Aguiar, Missing Millionaire, Still Missing As U.S. Coast Guard Ends Search

(Adds details from Fort Lauderdale police)

MIAMI, June 22 (Reuters) - The U.S. Coast Guard has ended its search for a Brazilian-born multimillionaire whose fishing boat washed up on a south Florida beach this week.

The Coast Guard said it called off the search late Thursday for Guma Aguiar, the 35-year-old founder of a Texas oil and gas company that he sold for a reported $2.55 billion in 2006.

The air-and-sea search spanned a 1,523-square-mile (3,944-sq-km) area, roughly the size of Rhode Island. But it yielded no trace of Aguiar, whose 31-foot (9.4-meter) fishing boat, the T.T. Zion, washed ashore on a Fort Lauderdale beach before dawn Wednesday with its navigation lights on and twin outboard engines still running.

Aguiar, a resident of Fort Lauderdale, had been involved with Jewish philanthropy since the sale of his company, Leor Energy, according to local media reports.

Fort Lauderdale police said surveillance footage from Aguiar's luxury waterside home showed him boarding the boat shortly before 7 p.m. EDT p.m. (2300 GMT) on Tuesday during a storm.

"Based on the surveillance footage, as well as witness statements, detectives are confident that Guma boarded the vessel by himself and departed from his dock as the sole occupant of the boat," a police statement said.

"No blood or signs of trauma were found on the vessel after it ran aground on the Fort Lauderdale beach," it added.

Police spokesman Travis Mandell said Aguiar's cell phone and wallet were found on the boat, along with other personal items, but added that it was "way too early for us to jump to any conclusions" about what happened to Aguiar.

Aguiar's mother, Ellen Aguiar, filed documents in Broward County court seeking to become a conservator, or temporary custodian, of his nearly $100 million fortune, according to the Sun Sentinel newspaper.

The petition, which says Aguiar's disappearance may have been due to "mental derangement," said he suffered from "severe bipolar disorder." (Reporting By Tom Brown; Editing by Stacey Joyce)