Riza Aziz, the stepson of former prime minister Najib Abdul Razak, was grilled by the MACC for nine hours today in relation to its probe into the scandal surrounding state investment firm 1MDB.

Riza left the commission's headquarters in Putrajaya – where Najib is also being detained – in a Black Audi car at 10.30pm, and did not stop to respond to questions from reporters...