The trial was the first of several related to the pilfering of billions from the 1MDB fund, a national scandal that led to the ouster of Mr. Najib’s party in 2018.
BANGKOK — A Malaysian court on Tuesday found Najib Razak, the country’s former prime minister, guilty of corruption on charges stemming from the disappearance of $4.5 billion from a government investment fund he once controlled.
The conviction of Mr. Najib, the scion of a political dynasty, was seen as a win for the rule of law even after his allies in government returned to power in March, taking control from the reformist government that ousted him in 2018.
Tuesday’s trial was the first of five related to the theft of billions from the 1Malaysia Development Berhad fund and Mr. Najib was found guilty on all seven charges of abuse of power, breach of trust and money laundering.
But experts said the verdict could be overturned on appeal.
The missing money was traced by prosecutors to the purchases of a megayacht and a Picasso painting, as well as an investment in the Hollywood blockbuster “The Wolf of Wall Street.” About $1 billion of the money ended up in Mr. Najib’s personal bank accounts, creating a national scandal that led to the ouster of his party, the United Malays National Organization, in elections two year ago.
The court rejected Mr. Najib’s defense that the theft was carried out without his knowledge by Jho Low, a wealthy Malaysian businessman who is accused of masterminding the crime and remains an international fugitive.
Mr. Najib, 67, still faces dozens of additional charges and at least two more trials. Many of the charges against him carry a sentence of up to 20 years.
But Mr. Najib remains a member of Parliament, and his party, popularly known as UMNO, returned to power in February, improving the chances that he will never spend a day behind bars.
In this trial, Mr. Najib faced seven charges of money laundering, criminal breach of trust and abuse of power for illegally receiving transfers of $9.8 million from SRC International, a former unit of the investment fund commonly known as 1MDB.
Mr. Najib does not lose his seat in parliament but would be prohibited from running for re-election unless his convictions are overturned on appeal.
Mr. Najib’s defense lawyers contended that he was a victim of a scam and did not know that money from the government fund had been deposited in his personal account.
The court also rejected the argument that Mr. Najib received the money as a gift from a Saudi royal and that he was unaware of the balance in his own account. “It would be extraordinary that the accused as the then-prime minister and finance minister did not know it,” said Judge Mohamad Nazlan Mohamad Ghazali, who delivered the verdict and presided over the 14-month trial in the Kuala Lumpur High Court.
In rejecting Mr. Najib’s defense and questioning his credibility, the judge cast doubt on whether the former prime minister’s legal strategy can be effective in his upcoming trials, which will focus on much larger amounts of money that went missing from 1MDB.
James Chin, a professor of Asian studies at the University of Tasmania and an expert on Malaysian politics, said it was likely that the guilty verdict would be overturned on appeal.
“People should not be celebrating, because in the Malaysian context, many of the judgments in these political cases get reversed in the appeals court,” he said. “I expect Najib to appeal and he will probably win the appeal. In the long term, I expect Najib to get away with it as long as UMNO is in power.”
In May, prosecutors dropped money-laundering charges against Mr. Najib’s stepson, the Hollywood producer Riza Aziz, who was accused of receiving $248 million in government funds.
The producer of “The Wolf of Wall Street,” Mr. Riza was allowed to walk away with $83 million under the terms of the agreement with the new attorney general, Idrus Harun.
Last week, the new government and Goldman Sachs reached a $3.9 billion settlement over the company’s role in the scandal. The previous government had sought more than $2.7 billion in fines and had charged more than a dozen executives with fraud. Under the settlement, criminal charges against the bank and the executives were dismissed.
Mahathir Mohamad, 95, who was prime minister from 1981 to 2003, came out of retirement in May 2018 to defeat Mr. Najib and UMNO, the party that Mr. Mahathir once led.
After the election, the authorities raided properties owned by Mr. Najib and his wife, Rosmah Mansour and seized more than $270 million in cash, jewelry, luxury handbags, tiaras and other valuables. Ms. Rosmah also faces corruption charges.
Mr. Mahathir pledged to pursue justice against Mr. Najib and his cronies but his coalition suffered from internal divisions and Mr. Mahathir stepped down in February.
In the months since, and against the backdrop of the coronavirus pandemic, Mr. Najib’s supporters have returned to power in what opponents have called a “coup” and a “backdoor government.”
Muhyiddin Yassin, who formed a coalition with UMNO, was appointed prime minister without an election and has since refused the opposition’s demands for a vote of confidence in Parliament.
Mr. Najib, whose father and uncle were both prime ministers, is part of Mr. Muhyiddin’s inner circle but does not hold a leadership post.
In cementing control after their return to power, Mr. Muhyiddin’s government has sought to crack down on independent news media, including Al Jazeera, which broadcast a 25-minute documentary earlier this month showing a military-style crackdown on undocumented migrant workers over coronavirus fears.
The authorities announced that they were investigating Al Jazeera for sedition, defamation and violating communications laws. The broadcaster said seven of its staff members have been questioned by the police.
