The man behind shocking allegations of corruption involving the country's highest office says he will not remain silent despite attempts to intimidate him.

Sofia Rini Buyong also appears to defend Shamsul Iskandar Mohd Akin, saying he gained nothing from issuing such letters as he was simply following an order from his boss.

Mahajoth Singh was told to appear before MACC on Sunday morning, a move condemned by lawyers as unlawful and a breach of client confidentiality.

The wife of businessman Albert Tei says her recording of the conduct of armed and masked officers inside their house was also deleted.

The businessman at the centre of an explosive scandal involving the nation's top office was interrogated by MACC officers at his home.

From now on, integrity should be measured only when individuals in government resign after being exposed for corruption.

This follows the emergence of a second video showing a woman stating that the MACC chief had always known about a plot said to be orchestrated by the prime minister and his aide to record incriminating videos of Sabah politicians.

The clip features a 'proxy' to Shamsul Iskandar Md Akin admitting shocking details to the businessman who exposed the Sabah mining scandal.

Zaid Ibrahim says the post of political secretary is a demotion for Shamsul Iskandar Md Akin, whose sacrifice ensured that Anwar Ibrahim could realise his prime ministerial ambitions.