Najib said he would testify in his defense when the trial resumes.
High Court Judge Mohamad Nazlan Mohamad Ghazali said the prosecution had established its case on charges of abuse of power, breach of trust and money laundering.
The seven charges relate to 42 million ringgit ($10.1 million) that allegedly went into Najib's bank accounts from a former unit of the 1MDB fund.
Najib is charged in four other cases in the scandal that led to his shocking election ouster last year. His wife, several officials from his government, and the U.S. bank Goldman Sachs face charges related to the scandal that led to investigations in several countries.
Najib, 66, has denied any wrongdoing and could face years in prison if convicted. The patrician former leader, whose father and uncles were the country's second and third prime ministers respectively, accuses Malaysia's new government of seeking political vengeance.
Prime Minister Mahathir Mohamad, leading an alliance that campaigned on an anti-corruption platform, won a history victory in the May 2018 elections that led to Malaysia's first change of government since independence from Britain in 1957.
Mahathir, 94, was premier for 22 years until his retirement in 2003 but made a political comeback amid anger over the 1MDB fiasco. His government soon reopened 1MDB investigations that had been quashed under Najib.
U.S. investigators say Najib's associates pilfered more than $4.5 billion from 1MDB between 2009 and 2014 and laundered the money through layers of bank accounts in the U.S. and other countries to finance Hollywood films and buy hotels, a luxury yacht, art works, jewelry and other extravagances. More than $700 million from the fund allegedly landed in Najib's bank account.
Truckloads of luggage stashed with cash, jewelry and hundreds of expensive designer bags worth a staggering 1.1 billion ringgit ($265 dollars) were seized from Najib's and his wife's home and other properties.
In all, he faces 42 charges of criminal breach of trust, graft, abuse of power and money laundering in the five criminal cases. His wife Rosmah Mansor and several former senior government officials have also been charged with graft. Malaysia also charged U.S. bank Goldman Sachs for allegedly misleading investors over bond sales it organized for 1MDB.
His second trial, the biggest and most complex, started in August. Najib faces four counts of abusing his power to receive more than $731 million from 2011 to 2014, and 21 other charges of receiving, using, and transferring illicit funds linked to 1MDB. Dates for the other trial have not been set.
Najib lawyers say he is the victim of a conspiracy by rogue bankers including one identified by U.S. investigators as the mastermind behind the 1MDB fiasco. Prosecutors say Najib was the real power behind the fraud in the fund and its local unit.