On the first day of a trial over the multibillion-dollar looting of a Malaysian government fund, US prosecutors on Monday accused a former Goldman Sachs banker of taking $35m in kickbacks as his defense team slammed the prosecution’s star witness as a bigamist who used their client as a fall guy.

Roger Ng, Goldman’s former head of investment banking in Malaysia, is charged with conspiring to launder money and violating anti-bribery law in his dealings with Malaysia’s 1MDB sovereign wealth fund.

The trial is renewing scrutiny of Goldman’s role in the international scandal that led to a 12-year jail sentence for Malaysia’s former prime minister Najib Razak.

“The defendant saw an opportunity to make millions of dollars by cheating, and he took it,” Brent Wible, a lawyer with the US Department of Justice, said in an opening statement on Monday.

Ng has pleaded not guilty and his lawyer has said he is a “fall guy” for one of the biggest financial scandals in Wall Street history.

The trial in Brooklyn federal court could last up to six weeks.

The scandal stems from some $6.5bn in bonds that Goldman helped 1MDB, launched by Razak to spur economic growth, sell from 2009 to 2014.

US prosecutors say Goldman earned $600m in fees from the deals, but that about $4.5bn of the funds raised was embezzled.

The bank in 2020 paid a $2.3bn fine, returned $600m in ill-gotten gains, and agreed for its Malaysian subsidiary to plead guilty in US court as part of a deal, known as a deferred prosecution agreement (DPA).

Wible said Ng helped two co-conspirators – his former boss, Timothy Leissner, and a Malaysian intermediary, Jho Low – launder funds embezzled from 1MDB and used some of the stolen money to bribe officials in the south-east Asian country to win business for Goldman.

Ng received $35m in kickbacks from Leissner, Wible said.

Leissner, a former partner for Goldman Sachs in Asia, in 2018 pleaded guilty to conspiracy to launder money and conspiracy to violate the Foreign Corrupt Practices Act (FCPA), in part by helping to pay $1.6bn in bribes. He is expected to testify as a government witness against Ng.

Wible said Leissner, who has not yet been sentenced, would testify against Ng as part of a cooperation agreement with prosecutors and as a result would get a lighter punishment. But Wible said Leissner’s testimony would be backed up by other evidence.

Defense lawyer Marc Agnifilo countered that Ng had no role in the scheme perpetrated by Low and Leissner and that he even warned Goldman management not to trust Low. He said the funds prosecutors called kickbacks in fact belonged to Ng’s wife and were derived from a business venture she had with Leissner’s ex-wife.

Agnifilo focused his opening statement largely on undermining Leissner, who is expected to testify for the government.

“Tim Leissner uses people,” Agnifilo told jurors, saying Leissner was “married to two different women at the same time, twice”.

“They’re not partners-in-crime. There’s a gulf between these two men a mile wide,” he said. “Leissner uses people. You will see this time and time again. He is trying to use my client ... to serve his jail time.”

Low, who was indicted alongside Ng in 2018, has not been arrested by US or Malaysian authorities. Malaysia has said he is in China, which Beijing has denied.