Video footage of an exchange between two Singapore Civil Defence Force officers taken on the night Corporal Kok Yuen Chin fell into a fire station pump well showed the officers arguing over whether one had told the other to push the full-time national serviceman into the well.

The video clip shown in court yesterday was taken from a police officer's body-worn camera when the police questioned the duo.

In it, Muhammad Nur Fatwa Mahmood, a staff sergeant, and Mohamed Farid Mohd Saleh, a first warrant officer, are seen disagreeing on whether the latter had given the instruction for the push.

On the night of May 13 last year, a group of SCDF servicemen was celebrating Cpl Kok's impending operationally-ready date at Tuas View Fire Station. Following a cake-cutting ceremony for Cpl Kok, 22, some officers carried him to the 12m-deep fire station pump well, where he later drowned after Nur Fatwa pushed him in.

Last October, Nur Fatwa was sentenced to one year and four weeks in jail for pushing Cpl Kok and telling another officer to delete footage of the incident.

Nur Fatwa, 34, who completed his sentence earlier this month, took the stand yesterday during the trial of Farid, the officer who has been accused of instigating the push.

Farid, 35, is contesting the charge of abetting a rash act causing death.

In the video footage , a police officer asks Farid if he is the one who gave the instruction to push Cpl Kok into the pump well.

"I didn't literally, like, ask him to... I just say 'so slow ah?', that's it," said an individual identified as Farid in the recording.

Another man identified as Nur Fatwa can be heard saying in Malay, "you said to push him in la, Rid," using Farid's nickname "Rid" to address him. Farid replies in Malay he had asked Cpl Kok to "sit there".

A while later, Nur Fatwa says in Malay: "Just now you already said, push him in, correct or not, don't play me out Farid."

Addressing the exchange in the video, Nur Fatwa, whom fellow officers call "Wa" for short, said he had said this as he felt betrayed that Farid did not want to admit that he had given the instruction.

Earlier, in a separate video showing the group gathered at the pump well before Cpl Kok was pushed in, Nur Fatwa also pointed out the moment that he remembered Farid saying "Wa, tolak dia", meaning "Wa, push him" in Malay.

Recounting the events in the immediate aftermath of the May 13 incident, Nur Fatwa said he had told the group of officers involved that they should be responsible for what they did together. However he said everyone responded with silence.

Earlier in the day, another witness, Staff Sergeant Al-Khudaifi Chang, 26, agreed during cross-examination by Farid's defence lawyer Chhabra Vinit that it was possible Nur Fatwa had said this to the group because he did not want to shoulder the responsibility of the incident alone.

SSgt Chang had also said Nur Fatwa had gone around asking other officers if they had heard Farid giving him the instruction to push Cpl Kok into the well, but none of them did. When asked why he had done so, Nur Fatwa said: "In a way, I wanted to get assurance from other people on whether they heard Farid say this."

The trial continues today when Nur Fatwa will undergo cross-examination.