Sometime in 2015, Malaysian investigators had to pull the brakes on investigations against prime minister Najib Abdul Razak on the 1MDB scandal.

Eventually, investigators decided that their only option left was to leak the investigation documents to the press.

According to Bradley Hope and Tom Wright in their book The Billion Dollar Whale, Malaysian investigators turned to them after they (the American journalists) had published an article in The Wall Street Journal (WSJ) that detailed how Najib allegedly used 1MDB as a slush fund.

"That story caught the eye of an intermediary for the (Malaysian) task force. A few days later, a Malaysian source met Simon Clark, a reporter with WSJ in London, to confirm the veracity of the documents - which the intermediary handed over hours later. Sarawak Report also received them.

"The files, copies of wire transfer documents into Najib's accounts as well as money-flow diagrams produced by the task force, were explosive," the book states.

Interestingly, the Malaysian sources of Hope and Wright had passed them encrypted computer files that could only be unlocked with the password "SaveMalaysia", a catchphrase that was used repeatedly by opposition parties in the run-up to the May 9 general election.

Najib 'furious' at British PM

The task force in question was initially conceived by former attorney-general Abdul Gani Patail in 2014, as part of a special revenue recovery unit.

During the first half of 2015, the task force primarily focused on the 1MDB and allegations that its funds were being abused by Najib. By July that year, Najib dismantled the task force and purged a number of those in high office.

According to Hope and Wright, Gani and the task force were just days away from laying charges against Najib, but were thwarted when "the police chief, supposedly part of the task force, decided to switch sides at the last minute and informed Najib of his impending arrest".

A few days after executing the purge, Najib received then British prime minister David Cameron in Kuala Lumpur, just after Cameron had delivered a speech on corruption in Singapore.

"In private, he pressed Najib on the 1MDB corruption claims and Malaysia’s human rights record. Najib was furious at the lecture by Cameron.

"His love affair with Western democracies was over," wrote the duo.