Dr Ang Yong Guan also said that Andy Lee Kee Liang's condition impaired his judgment, making him do things without realising the consequences or the nature of his acts.

The 24-year-old National University of Singapore student had said that negative voices prompted him to commit the offences against the boys aged between 14 and 15.

During cross-examination, Deputy Public Prosecutor Isaac Tan said Lee had said in a police statement in October 2007 that a few years before, he followed a boy into a lift and tried to touch his hand.

He asked Dr Ang if this raised doubt whether what Lee said about the voices was true.

Dr Ang replied that this was a period when Lee was not depressed and was able to control his impulse.

'He showed an inclination. He wanted to touch a boy but he could resist the temptation,' he added.

Asked by the DPP if it was homosexual inclination, the witness agreed.

While Lee had homosexual tendencies, he had also had meaningful relationships with three girlfriends before, said Dr Ang.

Dr Ang was called as one of the defence's expert witnesses to testify on Lee's mental state.

Read the full report in Thursday's edition of The Straits Times.