Lawyers acting for Najib Razak, Malaysia’s besieged ex-premier, said on Tuesday that they had quit, even as he and his family continue to face questions from agents investigating a multi-billion dollar corruption scandal involving a state-owned investment fund.

News of their resignation broke while Mr Najib’s wife, Rosmah Mansor, was being grilled for five hours by agents at the Malaysian Anti-Corruption Commission over a suspicious transfer of about $10.6 million from a subsidiary linked to the 1Malaysia Development Berhad (1MDB) fund.

The sum is just a fraction of the billions of dollars allegedly siphoned from 1MDB, which was set up by Mr Najib, in a controversy that was a major factor in his shock election defeat last month.

Mr Najib and his wife are currently barred from leaving the country after a fresh investigation into how the funds went missing was launched by the new government of Mahathir Mohamad, his former mentor.

The ex-prime minister has consistently denied any wrongdoing and was cleared of any offense in an earlier Malaysian enquiry.

However, on Tuesday, M Puravalen, a lawyer acting for Mr Najib and Rosmah Mansor told Reuters that he had “ceased acting” for the couple.