KUALA LUMPUR (Reuters) - Malaysian Prime Minister Mahathir Mohamad has vowed to bring back billions of dollars allegedly stolen from state fund 1Malaysia Development Bhd (1MDB), co-founded by his predecessor Najib Razak.

FILE PHOTO: A construction worker works in front of a 1Malaysia Development Berhad (1MDB) billboard at the Tun Razak Exchange development in Kuala Lumpur, Malaysia February 3, 2016. REUTERS/Olivia Harris/File Photo

The scandal has also embroiled U.S. bank Goldman Sachs GS.N, which Malaysia has accused of misleading investors over three bond sales totaling $6.5 billion that the bank helped raise for 1MDB. Malaysian authorities say they are seeking $7.5 billion in compensation from Goldman.

WHAT IS 1MDB?

The fund was set up in 2009 with the help of Malaysian financier Low Taek Jho, better known as Jho Low, to promote economic development.

Najib chaired its advisory board until 2016.

HOW DID BILLIONS GO MISSING?

1MDB raised billions of dollars in bonds for use in investment projects and joint ventures between 2009 and 2013.

The U.S. Department of Justice (DoJ) said $4.5 billion was diverted to offshore bank accounts and shell companies, many of which were linked to Low.

Malaysian authorities say at least $4.3 billion more has yet to be accounted for.

The siphoned funds were allegedly used to buy luxury assets and real estate for Low and his associates, including a private jet, a luxury yacht, artwork by Pablo Picasso and Claude Monet, and diamond jewelry, U.S. lawsuits said.

Some of the funds were used to finance Hollywood films “The Wolf of Wall Street” and “Dumb and Dumber To”, produced by Red Granite, a film company co-founded by Riza Aziz, Najib’s stepson and a friend of Low’s.

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HOW WAS NAJIB INVOLVED?

A person described in U.S. lawsuits as “Malaysian Official 1” allegedly received more than $1 billion in 1MDB funds, some of which was used to buy jewelry for the person’s wife.

U.S. and Malaysian sources have said the official refers to Najib. Riza and Najib have denied wrongdoing.

Najib, who lost an election in May 2018, has been hit with 42 criminal charges over losses at 1MDB and other state entities.

He has plead not guilty, saying that he was misled by Low and that the funds in his account were donations from the Saudi royal family.

Najib’s wife, Rosmah Mansor, has also been charged with money laundering and bribery.

HOW ARE AUTHORITIES INVESTIGATING 1MDB?

At least six countries have launched money laundering, financial mismanagement and criminal probes into 1MDB dealings.

Malaysia has also charged Low, Low’s associates and former 1MDB officials, while forfeiture lawsuits have been filed to recover funds originating from 1MDB.

Prosecutors also charged three Goldman units, as well as 17 current and former directors of the bank.

Malaysia rejected an offer from Goldman of less than $2 billion in compensation, Mahathir has said.

The United States has charged Low, former Goldman bankers Roger Ng and Tim Leissner, as well as U.S. rapper Pras Michel, said to be friends with Low.

In November, the DoJ struck a deal to recoup $1 billion from the sale of seized assets linked to Low, a record haul for a U.S. anti-corruption probe.

As part of a review into 1MDB-related transactions, Singapore shut the local units of Swiss bank BSI and Falcon Bank in 2016, froze millions of dollars in bank accounts, and charged several private bankers.

Since 2016, Swiss financial watchdog FINMA has confiscated more than $100 million in illicit profits from 1MDB-related deals by banks BSI, Falcon, and Coutts & Co. BSI has challenged the seizure.

WHERE IS LOW NOW?

Low has denied wrongdoing and his whereabouts are unknown. He has been granted asylum in a third country, his spokesman has said, declining to identify the country.

Malaysian officials have said Low was believed to be hiding out in China.