An outgoing Malaysian Anti-Corruption Commission deputy commissioner has dismissed speculation that there are hidden hands hiding guilty parties in the 1MDB case.

MACC deputy commissioner (management and professionalism) Zakaria Jaffar said there was usually a simpler explanation.

"In the 30 over years I have served as a graft buster, there has never been hidden hands.

"What usually happens though is that the witnesses to the case don't come forward, and cooperate with us," he said at a press conference in Kuala Lumpur today.

He said this when asked about former deputy prime minister Muhyiddin Yassin's ( photo ) concerns about hidden hands interfering with the 1MDB probe.

The MACC is currently seeking three key witnesses in their investigations on former 1MDB subsidiary SRC International.

Two of them, SRC International, managing director Nik Faisal Ariff Nik Othman Kamil, and SRC director Suboh Mohd Yassin are believed to be overseas.

Zakaria was speaking to reporters after his retirement ceremony at the Anti-Corruption Academy.

He has served as a graft buster for 33 years.

MACC chief Abu Kassim Mohamed made an emotionally charged farewell speech, describing Zakaria as one of the most excellent deputy commissioners to have served the graft buster.

"He is retiring at a time...when we are facing great challenges," he said, pausing a moment to wipe a tear and regain his composure.

Zakaria was replaced by Mohamad Jamidan Abdullah, who took over his duties on Aug 1.