A billionaire developer from Macau arrested in the U.S. on charges he brought $4.5 million into the country and lied about its purpose to authorities was ordered to be held without bail by a federal judge in New York.

Ng Lap Seng, 68, and an employee whom the government called his “right-hand man” were accused of falsely claiming they brought the money into the U.S. on trips from 2013 to 2015 to spend on art, antiques, real estate and gambling. Ng is charged with failing to disclose to customs agents that he was carrying more than $10,000 when he entered the U.S.

Ng has vast wealth that might allow him to easily evade authorities if he’s released on bail, Assistant U.S. Attorney Janis Echenberg told a judge Monday. He has a net worth of about $1.8 billion, holds at least $1 billion in Chinese real estate, earns about $25 million a month and has access to $30 million worth of private planes, she said.

Ng was arrested Sept. 19. Details about the government’s investigation of him emerged at a hearing that day for Jeff Yin, 29, who the government described as Ng’s assistant.

Yin talked to investigators and “admitted among other things that he was transmitting money on behalf of Mr. Ng to pay people to do unlawful things,” Assistant U.S. Attorney Daniel Richenthal said, according to a recording of the Sept. 19 hearing.

Prosecutors also have evidence that Ng wired at least $19 million to U.S. bank accounts and individuals. Ng and Yin were en route to leave the U.S. from Teterboro Airport in New Jersey on a private plane when they were arrested, Richenthal said.

Ng avoided the U.S. in the past after he was linked to a separate investigation tied to the illegal wiring of money to U.S. political parties, Echenberg said. Once he learned that a congressional inquiry was under way, he stayed out of the U.S. for at least four years, according to the prosecutor. Ng also evaded a grand jury subpoena, Echenberg told U.S. Magistrate Judge Sarah Netburn at Monday’s bail hearing.

Defense lawyer Kevin Tung argued that Ng’s arrest stemmed from a misunderstanding “because he comes from a different culture.” Tung said Ng is an elected official in Macau, likening him to a senator or congressman.

“He’s rich, that’s not an element of being a criminal,” said Tung, who offered to put up Ng’s $3.8 million apartment on Manhattan’s Upper East Side as part of his bond. He also said his client doesn’t understand English and may not have understood the significance of a grand jury subpoena.

“There’s a cultural difference that people don’t know that when they come into this country carrying lots of cash, there may be problems,” Tung said.