SINGAPORE — Two more tuition centre students who took the stand in an ongoing GCE O-Level examinations cheating trial on Thursday (Aug 2) said that they were told to delete conversations from their mobile phones to cover their tracks.

One of the students who exposed the scheme when he was caught cheating during the English Paper 1 exam claimed that he was sent home to China on the same evening, lest he be "caught by the police".

The students were the prosecution's witnesses in the trial of 52-year-old Zeus Education Centre principal Poh Yuan Nie, also known as Pony Poh, and her two accomplices — her niece Fiona Poh Min, 30, and China national Feng Riwen, 25.

They are accused of helping six students from China cheat at the 2016 O-Level exams. Two of the students testified in April, with another one testifying in court on Wednesday. The three students were: Mr Chen Xiang, 19, Mr Zhou Zice, 17, and Mr Zhang Jinlu, 20.

On Thursday, Ms Wang Fangfei, 19, told the court in Mandarin that she received a call on her mobile phone when she was heading home after her English Paper 1 and 2 exams on Oct 24, 2016.

While she was not sure who the caller was, the female caller instructed her to "delete all conversation records on my phone", and she did so.

Before that, a female teacher allegedly told her not to go to Zeus the next day to pick up the Bluetooth devices used for cheating, but to head directly to the exam venue for her Additional Mathematics exam.

"I think she said that one person was discovered by the invigilator for cheating, so I don't have to go back to take the devices," said Ms Wang.

Sometime after, she received another call telling her not to sit for subsequent exams.

It was revealed in court earlier that Fiona Poh, Feng and another tutor, Tan Jia Yan, 32, had allegedly outfitted the students with Bluetooth devices, as well as a skin-coloured in-ear earphones before they went into the exam centres.

These devices were linked to mobile phones, which were concealed under the students' clothing.

Either Fiona Poh or Tan — who used to work at Zeus and pleaded guilty in April to 27 charges of cheating — also sat for the exams. They allegedly registered separately as private candidates, and used a hidden iPhone affixed to their chests to help the six students cheat.

Once the exams began, they allegedly used the video-calling app FaceTime to broadcast the exam papers back to their accomplices at the tuition agency. They would then call the students individually, and read out the answers to them.

Mr Chen Yi, 20, testified that after he was caught cheating, he went back to Zeus and told Pony Poh, Fiona Poh, Feng and Tan what had happened. "They looked quite nervous," he said.

Claiming that Pony Poh told him that he had to return to China that same night or be caught by the police, he alleged that she asked another student to change S$1,000 into renminbi. She also allegedly told him to stay in China for a week while she figured out a way to get him back to Singapore.

Tan then bought him a plane ticket, and Fiona Poh asked for the password to his phone so she could "remotely" delete conversations from there.

"She said that if I was arrested, I would implicate many others," he said.

Mr Chen Yi left for China that night. It was not stated in court when he returned to Singapore.

He also provided more details in court on how he was caught on Oct 24, 2016. When Feng allegedly called him repeatedly during the English Paper 1 exam, the speaker in his earpiece malfunctioned and began emitting sounds.

An invigilator noticed this, and called him into the office, where he was told to write down everything about the cheating scheme. He also showed them the Bluetooth devices that were taped to his body. Afterwards, he took a taxi back to Zeus.

During cross-examination, Pony Poh's lawyer, Mr Peter Keith Fernando, again sought to discredit the witness.

Mr Chen Yi confessed that he was not even registered for the Physics/Chemistry practical exam when he allegedly began cheating, and that he was only told to sit for the exam that morning.

Both Mr Chen Yi and Ms Wang testified earlier that Pony Poh had called them into her office separately the day before, and told them of a "secret" that would only be revealed the next day. She also allegedly told them to come in earlier the next day, which was when the Bluetooth devices were first strapped on them.

The lawyer grilled Mr Chen Yi on why he had agreed to sit for a "totally foreign subject" if his agent from China had said he only needed to take the English, Mathematics and Chinese exams.

Mr Chen Yi said Pony Poh told him that he had to go for the science exam, even after he said he had not taken it before.

He added: "She said not to worry and that we will help you, and if you don't follow our instructions, you will bear the consequences on your own. So we had no choice but to follow."

When Mr Fernando pressed him on why he did not leave that morning and return home, he said that his mother had "signed a contract with the agent", which purportedly bore a clause that they would "bear the consequences" if they did not follow instructions.

Mr Fernando also accused Mr Chen Yi of colluding with the investigating officer — who was present in court and is set to testify — as the testimony he gave while being questioned by the prosecution did not seem to line up with what he said under cross-examination.

The trial continues on Friday.