The media reported yesterday that Rosmah had to present herself at the MACC headquarters in Putrajaya this morning to assist the graft busters in their investigations.
"Rosmah has been arrested", her lawyer K. Kumaraendran told AFP after she was questioned for hours at the Malaysian Anti-Corruption Commission (MACC) on Wednesday.
She will be brought to court on Thursday to face charges related to the anti-money laundering law.
She was summoned regarding beleaguered sovereign wealth fund 1Malaysia Development Berhad's (1MDB) subsidiary SRC International Sdn Bhd and the anti-graft body's investigation into money laundering.
She made no comment to reporters.
He said then that it was up to the AG to prosecute Rosmah.
Police found hundreds of luxury handbags, jewelry and cash - worth more than $266 million - during raids on apartments linked to the family shortly after Najib's shocking electoral defeat in May. Najib was said to have been taken into the building not through the main entrance.
Rosmah smiled and shook hands with officers of the anti-graft agency as she arrived at its headquarters at around 0300 GMT, wearing a headscarf, and traditional Malay garb of floor-length skirt and a blouse in lime-green.
The Umno Supreme Council member was referring to Najib's expected presence at the courts tomorrow for his first ever case management, after pleading not guilty to multiple charges of corruption and criminal breach of trust.
He is also set to be in court on Thursday for a pre-trial hearing of charges related to 1MDB filed against him.
Rosmah arrives at the Malaysian Anti-Corruption Commission (MACC) in Putrajaya.
Ms Nooryana posted a picture of her mother holding her as a toddler, and vowed "we will persevere".
Najib also showed up at the anti-money laundering and anti-terror financing division of the police to give a statement.
Corruption accusations have dogged Mr Najib for years, and came to a head in 2015, when the Wall Street Journal reported that almost US$700 million ($982 million) in 1MDB funds were diverted to his personal bank account.