New MACC chief Mohd Shukri Abdull told reporters to expect a "special briefing" on Tuesday.
Less than two weeks after from being voted out of office after nearly three decades in power, Najib was ordered to explain a suspicious transfer of 42 million ringgit ($10.6 million, €9 million) into his bank account.
Shukri said his agency had been poised to launch a case in 2015 against Najib but had been stopped in its tracks by the sacking of the attorney-general. "I am not a rogue", he said. He hadn't been brought in for arrest, Mr. Shukri said.
"I was sent a bullet to my house".
He then explained he was followed all the way to the United States by a personnel from former prime minister Datuk Seri Najib Razak's administration in July that year.
"I am amazed that even though I am no longer the prime minister, there are so many people at this event", he said during a ceremony opening a branch office of his United Malays National Organisation (UMNO).
The shock election result upended Malaysia's political order, as it was the first defeat for a coalition that had governed the Southeast Asian nation since its independence from colonial rule in 1957.
On Friday, a team from the MACC arrived at Najib's home at Taman Duta to deliver a notice requiring the Pekan Member of Parliament to give statement at the agency headquarters today to assist in the investigations into the SRC International Sdn Bhd case.
Several current and former senior government officials will lead the task force, including Abdul Gani Patail, the former attorney-general who was removed from his post in 2015 as he was leading investigations into 1MDB.
Najib has said $681 million of funds deposited in his personal bank account were a donation from a Saudi royal, rebutting reports that the funds came from 1MDB.
The initial focus of the MACC's new probe is on how 42 million ringgit ($10.6 million) went from SRC International to Najib's account.
Ownership of SRC had been transferred to Malaysia's finance ministry by February 2012, lowering 1MDB's gearing ratio to 9.5 times, from 12 times, and removing the state guarantee for 1MDB, according to the report.
Najib has been barred from leaving Malaysia as the new government investigates accusations he took part in the looting of billions of dollars from sovereign wealth fund 1MDB in a vast conspiracy of fraud and money-laundering.
The U.S. filed forfeiture complaints in 2016 and 2017 seeking to recover over $1.7 billion in assets traceable to funds allegedly misappropriated from 1MDB. USA investigators say Najib's associates stole and laundered $4.5 billion from the fund, some of which landed in Najib's bank account.