The man, who is the sole eyewitness of the December 16 gang rape of a 23-year-old woman in a moving bus, was on Monday cross-examined by the defence in the fast-track court trying the case.
The youth, a software engineer, had testified as a witness for the prosecution during in-camera proceedings against the five accused, who have pleaded not guilty to the charges of rape and murder framed against them.
His cross-examination will continue on Tuesday.
Apart from the victim’s friend, three others, including a person who had seen the accused destroying evidence after commission of the crime, have already deposed in court.
The 23-year-old woman had died on December 29, 2012 in a Singapore hospital.