 -- The casino company run by the principal financial backer of Newt Gingrich's presidential bid, Sheldon Adelson, has been under criminal investigation for the last year by the Department of Justice and the Securities Exchange Commission for alleged bribery of foreign officials, according to corporate documents.

In a separate civil lawsuit, a former executive of the company has alleged that Adelson ordered him to keep quiet about sensitive issues at the Sands casinos on the Chinese island of Macau, including the casinos' alleged "involvement with Chinese organized crime groups, known as Triads, connected to the junket business." The triads -- Chinese organized crime syndicates -- are allegedly involved in organizing high stakes gambling junkets for wealthy Chinese travelers.

In its filings with the SEC, Adelson's company says it became aware of the investigation in February 2011 when it received a subpoena from the SEC requesting "documents relating to its compliance with the Foreign Corrupt Practices Act." The company said it "intends to cooperate with the investigation," which it said may have been triggered by the allegations in the lawsuit by Steven C. Jacobs, a former Sands executive who says he helped run the Macau operation. The federal investigation was first reported last year by Las Vegas newspapers and the financial press.

At a gaming forum last year, Adelson said the lawsuit "is not a serious case" and that the federal investigations would find no wrongdoing. "When the smoke clears, I am 1,000 percent positive that there won't be any fire below it."

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Adelson and his wife have given at least $10 million to the pro-Gingrich Super PAC "Winning our Future" and ABC News political analyst Amy Walter said the Adelsons' money "has been a major factor in keeping Newt Gingrich's campaign alive." The candidate and the Super PAC are not legally allowed to coordinate their efforts, but the political action committee's goals are unambiguous, as they finance ads supporting Gingrich and attacking his opponents.

ABC News received no response to calls and emails to the Gingrich campaign seeking comment.

Sheldon Adelson Owns 49 Percent of Sands Company

Adelson has become a symbol of the new, no-holds-barred environment for campaign money, with recent Supreme Court rulings opening the door for one wealthy individual to single-handedly bankroll one of the costliest aspects of a political campaign: television advertising. Adelson, who is one of America's richest people, has the means to do so. The billionaire owns 49 percent of the Sands casino company and as chairman, is directly involved in its operations. Its operations in Macau have made the Sands the world's leading gambling operation.

But the company operates where corruption is described as "a major and growing problem," according to a 2011 report from the U.S. Congressional-Executive Commission on China.

"The growth of gambling in Macau, fueled by money from mainland Chinese gamblers and the growth of U.S.-owned casinos, has been accompanied by widespread corruption, organized crime and money laundering," the commission found.

The Venetian-Macao, a casino owned by the Las Vegas Sands Corporation, was also the subject of a reported "sex-trade crackdown" that occurred in 2010 on the same day Adelson arrived on the island for meetings with government leaders in Macau, according to published accounts in 2010. Chinese press reported that authorities found more than 100 prostitutes inside the casino.

Jacobs alleges in his lawsuit that Adelson demanded that Jacobs refrain from telling the corporate board of Sands China about issues including "junkets and triads." He also alleges that Adelson wanted to investigate high-ranking Macau officials to provide him "leverage" to thwart any initiatives that would hurt the company.

"The triads are making a ton of money off the gambling industry," said Ko-lin Chin, a Rutgers University criminal justice professor who is one of the leading experts on Chinese organized crime. "They are still there, they are still very active."

Sands corporate spokesman Ron Reese told ABC News he did not wish to comment, instead pointing to earlier statements that Adelson has made about the case.

Adelson said at the gaming forum last year the lawsuit "is pure threatening, blackmailing and extortion" and said the case created a "foundation of lies" upon which the subsequent investigations have been based. He told the Wall Street Journal in March "we have a substantial list of reasons why Steve Jacobs was fired for cause and interestingly he has not refuted a single one of them. Instead, he has attempted to explain his termination by using outright lies and fabrications which seem to have their origins in delusion."

Last year, a judge rejected a motion by Las Vegas Sands to dismiss the case.

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