PUTRAJAYA, Malaysia (AP) — Malaysia's top court Monday began hearing a final appeal by former Prime Minister Najib Razak to toss out his graft conviction linked to the massive looting of the 1MDB state fund.

He would become Malaysia's first former prime minister to be imprisoned if his case fails. Najib, 69, has reiterated his innocence and has been out on bail pending his appeals.

He was sentenced to 12 years in jail by a high court in July 2020 after being found guilty of abuse of power, criminal breach of trust and money laundering for illegally receiving 42 million ringgit ($9.4 million) from SRC International, a former unit of 1MDB.

The Court of Appeal upheld the conviction and sentence in December, describing the case as a “national embarrassment." His last avenue, the Federal Court, is scheduled to hear the case until Aug. 26.

Najib has changed to a new team of lawyers for his final appeal. His defense team is attempting to introduce new evidence that would spark a retrial, citing conflict of interest by the high court judge who convicted Najib.

1MDB was a development fund Najib set up shortly after taking power in 2009. Investigators allege at least $4.5 billion was stolen from the fund and laundered by Najib’s associates.

The scandal sparked investigations in the U.S. and several other countries and caused the downfall of Najib's government in 2018 elections. Najib faces a total of 42 charges in five separate trials linked to 1MDB, and his wife is also on trial for corruption.

Despite his graft conviction, Najib remains politically influential. His United Malays National Organization leads the current government after defections of lawmakers caused the collapse of the reformist government that won the 2018 polls.

Najib is still a lawmaker pending his appeal but he cannot contest if an early general election is called. National polls are not due until the second half of 2023, but there have been strong calls from UMNO leaders for early elections.