The son of one of Malaysia's founding fathers, Najib Razak was groomed for the prime minister's post from a young age.

But after running the country for nine years he now faces more than a decade in jail for corruption in a spectacular fall over his links to the misuse of billions in public money.

Malaysia's highest court on Tuesday upheld Najib's 12-year jail sentence over the theft of cash from state fund 1MDB, slamming shut the door on any further political ambitions the former leader may have held.

Since his shock election defeat in May 2018, Najib has faced a tightening noose as successive governments ramped up investigations into the allegations of graft that have hung over him and wife Rosmah Mansor.

Later that year Najib was found guilty of abuse of power, money laundering and criminal breach of trust over the 1MDB scandal.

The convictions relate to his role in diverting 42 million ringgit (about $10 million) from SRC International, a unit of 1MDB, into his personal bank accounts.

Najib's downfall is a far cry from 2009 when he first took office offering hope for many in Malaysia longing for an end to the repressive tactics deployed by a once-invincible coalition that ruled for six decades.

He initially espoused liberal political views and replaced security laws widely criticised as stifling dissent.

But the British-educated Najib was seen by many Malaysians as an aloof elitist with little understanding of common people.

That perception was accentuated by frequent tone-deaf gaffes as well as policies unpopular with the poor, such as a sales tax introduced in 2015 that is now set to be scrapped.

His wife Rosmah was also a constant lightning rod for critics due to her imperious manner and elaborately coiffed hair, which she once complained cost her 1,200 ringgit ($270) to style. Malaysia's minimum monthly wage at the time was 900 ringgit.

Then-prime minister Mahathir Mohamad has said Najib told him in 2015 that "cash is king" in maintaining political support in Malaysia, a phrase that opponents turned against Najib as a sign of his hubris and corruption.

Money and power appeared to act as a firewall protecting Najib through a scandal involving Malaysia's 2002 purchase of French submarines while he was defence minister, a deal brokered by a close associate.

Allegations later emerged of huge kickbacks to Malaysian officials to secure the deal, and the murky episode was punctuated by the murder of a Mongolian woman involved in the negotiations.

Altantuya Shaariibuu was shot dead and her body blown up near Kuala Lumpur using military-grade explosives.

Two officers in a special unit that guarded Malaysian ministers were convicted of the killing, but suspicion that Najib and Rosmah were involved hovered for years, with Najib at one point forced to deny he had an affair with the 28-year-old Altantuya.

The final straw was 1MDB, a fund Najib launched in 2009 to promote economic development.

Soon after he won a second term in 2013, 1MDB slid into a massive debt hole and allegations surfaced that money was missing.

Public disgust with reports that emerged around 2015 detailing the plunder of the sovereign wealth fund snowballed into a Mahathir-led electoral tsunami that left Najib in the crosshairs of police.

US authorities say Najib's entourage used hundreds of millions in diverted 1MDB funds to purchase high-end real estate in Los Angeles, New York and London.

Other spending on the public purse included a Monet painting for $35 million, a $5.5 million work by Van Gogh, a $35 million Bombardier jet and financing for the 2013 Hollywood film "The Wolf of Wall Street", which was produced by Najib's stepson Riza Aziz.

A 2015 investigative report by the New York Times also alleged that millions of dollars were used to purchase jewellery for Rosmah.

In a speech in December 2017, then-US attorney general Jeff Sessions said of the scandal: "This is kleptocracy at its worst."

Najib steadfastly denied wrongdoing while persecuting his accusers and shutting down media outlets that reported on the affair.

In the end, the 69-year-old cut a dejected figure in court as the final verdict was read Tuesday.

"We were told he has been taken to Kajang Prison, south of the capital Kuala Lumpur," Nur Sharmila Shaheen, his daughter-in-law, told AFP.