The brother and nephew of former United Nations Secretary General Ban Ki-moon have been charged with conspiracy to bribe a government official.
New York officials accuse Mr Ban's younger brother, Ban Ki-sang, and his nephew, Joo Hyun Bahn, offering money to a Middle Eastern official.
They allege bribes were given to entice the official to use government funding to buy their building project.
Ban Ki-moon served as UN secretary general from 2007 until 2016.
He was succeeded by former Portuguese Prime Minister Antonio Guterres on 1 January 2017.
In early 2013, the South Korean construction firm Keangnam, of which Mr Ban's brother was an executive, was faced with growing debt and sought to sell a building complex in Vietnam known as Landmark 72.
Prosecutors alleged on Tuesday that he and his son, a Manhattan estate agent, stood to make millions of dollars in commission on the sale, valued at up to $800m (£657m).
The two men paid millions of dollars in bribes and tried to trade on the prominence of their South Korean family in order to persuade a Middle Eastern official from an unnamed country to arrange a purchase of the complex by that country's sovereign wealth fund.