NUS law professor Tey Tsun Hang, on trial for corruption, this morning accused an anti-graft officer of "selective perfect memory".

He was cross-examining Ms Png Chen Chen, a senior special investigator with the Corrupt Practices Investigation Bureau, who had taken prosecution witness Darinne Ko's statement last year.

Tey said that Ms Png needed to refer to her investigation diary and notes when asked about what she did on April 2 and 3 last year. Yet, he said, she could clearly remember verbatim statements from Ms Ko which she recorded on April 2 last year.

To this, Ms Png said her notes helped her to "recall details" of that day better.

Tey faces six charges of corruptly obtaining gifts and two occasions of sex from Ko in exchange for better grades. Today is day five of the trial, which is set for nine days.