Benjamin Lim was calm when he was interviewed by the police at North View Secondary School, where he studied. But he turned fidgety after speaking to his mother on his mobile phone before he was taken to a police station.

This was the testimony of school principal Chen Fook Pang and school counsellor Karry Lung when they took the stand yesterday at the coroner's inquiry into the death of 14-year-old Benjamin.

Mr Chen, who was the first from the school to give testimony, said the teenager "cooperated very well" after police came looking for a suspect in a case of alleged molestation involving an 11-year-old girl.

Benjamin did not look anxious when speaking with police inspector Poh Wee Teck, he added.

But he appeared anxious after speaking to his mother on his mobile phone, when she was informed that he was being taken to a police station, said Mr Chen, who had asked to let Benjamin make the call.

Benjamin passed the phone to Inspector Poh, said the principal. The inspector told the boy's mother in Mandarin that the police needed to take him back to Ang Mo Kio Police Division to assist with investigations, and that the investigation officer would tell her later how to pick up her son.

"At this point, I could hear Benjamin's mother speaking very loudly, even though the phone was not on speaker mode," added Mr Chen, who said he could not make out what was being said.

Madam Lung said that Benjamin was coping well during the interview, which took place in the principal's office, even though he seemed "slightly stressed".

She explained that she did not see a need to step in.

But things changed when he was speaking to his mother. "I noticed that he started frowning, and his replies became softer," she said.

Sensing that the conversation "was not doing him any good", she signalled to the room at large to end the exchange.

Mr Chen also told the court that before he let the police interview Benjamin, he had made three requests to them - all of which were acceded to.

He told the officers that he wanted to talk to Benjamin first, without them present.

He also asked that only one officer spoke to Benjamin, as five were too many, and that school staff be allowed to sit in.

Mr Chen explained that he wanted to speak to Benjamin first to check on his well-being. This was part of the school's "common understanding with the police", going by previous cases.

He admitted he had "pushed (his) luck a bit further" by requesting that staff be present during the interview as well. This was not necessarily the case in previous instances, added Mr Chen.