It has been learnt that the investigation into 1MDB dealings with Abu Dhabi wealth fund International Petroleum Investment Company (IPIC), which saw the former prime minister Najib Abdul Razak grilled twice by MACC this month, made progress following information obtained from a person involved in the matter.

The person, who carries a "Datuk" title, was appointed by Najib as an intermediary between the two companies some years ago, a source with the knowledge of the investigation told Malaysiakini.

The intermediary had surrendered to MACC in June, and is believed to have been put under a witness protection programme.

This is the same person who was also on the MACC's wanted list in 2015 to facilitate the commission's investigation into 1MDB.

It is learned that in MACC's series of investigations this month, the agency had probed Najib based on statements recorded from the person.

The source told Malaysiakini that while Najib was responsible for appointing the 1MDB-IPIC intermediary, the former prime minister had allegedly told investigators that he had trusted his appointee and had not kept tabs on the person's work deployments.

Meanwhile, a source close to the investigation has confirmed to Malaysiakini that Najib will face six charges on Thursday following the investigation into the matter. 

New Straits Times (NST) had earlier reported that Najib is expected to face at least four more charges this week, related to 1MDB's dealings with IPIC.

It said that prosecutors would hold Najib liable for his role in last year’s debt settlement between the two parties.

Sources told the NST that MACC investigators had looked into how the former administration had settled a debt using taxpayers’ money, and who had authorised the payment - done allegedly “without even the approval of the cabinet”.

A settlement was reached last year by the Finance Ministry to pay US$1.2 billion (RM5.04 billion) to IPIC over a US$6.5 billion claim made by the latter. Najib was also the finance minister then.