A diving superintendent of a ship cleaning company was sentenced to two years' jail yesterday over the death of a diver under his watch.

Mohd Zalkarnain Mohd Salleh, 55, had endorsed the plan of having two divers working underwater at the same time despite knowing that it was not safe. He also failed to monitor the video feed of freelance commercial diver Seet Choon Heng, and did not notice his repeated cries for help.

Zalkarnain pleaded guilty yesterday to one count of aiding diving supervisor Raden Roslan Mohd in causing Mr Seet's death and another count of forging credentials to secure his job. Raden was given 12 months' jail in June last year for rash acts causing Mr Seet's death.

Though a qualified diver, Zalkarnain had forged documents to get the job of diving superintendent at Mola Subsea Services in late 2017.

On May 5, 2018, Mr Seet dived underwater at around noon to clean the ship's stern under Raden's instruction. Shortly after, Raden told a second diver to dive in and polish the propeller. It meant there were no divers on standby to help if the two underwater ran into trouble.

While Mr Seet was underwater, Raden turned down his radio volume so he could hear the other diver more clearly. At around 1.40pm, Zalkarnain turned his back to the screen monitoring the divers to discuss a dive plan with Raden. He did this despite knowing it put both divers at risk of death as they could be pulled away by a current, or communication cables could be severed.

It was at this juncture that Mr Seet realised he could not ascend to the surface as his communication cord was entangled with the seabed. He called for help over the intercom for about a minute, but there was no response. He then removed his helmet and tried to swim to the surface but struggled for about 45 seconds before he ran out of air and sank to the sea floor.

Close to six minutes passed before Zalkarnain noticed his video feed had gone black. With no diver on standby, Raden instructed the other diver underwater to look for Mr Seet. By this time, the Maritime and Port Authority had learnt of the disappearance and ordered the crew to stop all diving operations.

At around 6.30pm on May 7, two days later, Mr Seet's body was found in the sea off Sentosa, near where he had gone missing.

Yesterday, Deputy Public Prosecutor Andre Chong sought at least two years and three months' jail for Zalkarnain to signal that his cavalier attitude to life and safety should not be tolerated. "By failing to deploy the necessary safety personnel and failing to intervene when Raden left the deceased unmonitored, Zalkarnain put it out of his power entirely to detect the deceased's distress and effect a timely rescue," he said.

Zalkarnain's lawyer Muslim Albakri said in mitigation that Zalkarnain had played no part in Raden turning off Mr Seet's radio feed, and that the simultaneous dive was the fault of the whole team.