Law professor Tey Tsun Hang, 41, in his cross-examination of former student Darinne Ko on Monday, sought to prove that there was no corrupt intent in the grades he gave her, nor any promises of favours in return for her gifts.
He produced e-mail correspondence between him and a vendor where he enquired about a Montblanc pen to prove that this was an item that he did not expect as a gift and wanted to purchase on his own.
The $750 pen is among the gifts that Tey had received from Ms Ko. Tey on Monday also went through Ms Ko's grades to show that they were warranted, and asked her questions about whether the gifts were pre-empted.
During his cross-examination of her, Tey asked Ms Ko about the interrogration process, where she had alleged that she was coerced into giving statements that fit the "material charges brought against" him.
He is facing six charges of corruptly obtaining gifts and sex from her in exchange for better grades. The alleged offences took place between May and July 2010. On the first day of the trial, which started last Thursday, Ms Ko had painted a picture of love which flourished for a time between her and Tey, who was once her professor.
Ms Ko, the witness at the centre of a sex-for-grades trial, will appear on the stand again on Tuesday for further cross-examination. The trial resumes at 9.30am on Tuesday.