Ms Darinne Ko, the star witness in the centre of the sex-for-grades case, arrived at the Subordinate Courts at 8.30am Friday.

She will return to the witness stand to give evidence for a second day as the prosecution seeks to make its case against law professor Tey Tsun Hang, 41.

Ms Ko had on the first day of the trial, which started yesterday, painted a picture of love which flourished for a time between her and Tey, who was once her professor.

She told the court they exchanged "I love you's" when she was a student at the National University of Singapore (NUS).

She bought him gifts and they had sex twice in July 2010.

Tey, who arrived at court later at about 9.05am, 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.

The gifts included a $740 Montblanc pen, two tailored shirts worth $236.20, a $160 iPod touch, and a $1,278.60 payment for a dinner Tey hosted. The sex took place in his office at NUS on July24 and 28, 2010.

Presenting its case yesterday, the prosecution made clear that "the cloak of love provides no cover for what was essentially an NUS law professor taking advantage of his student".

The trial starts at 9.30am.

Tey, who is conducting his own defence, may have the chance to cross-examine Ms Ko later today.