Prosecutors yesterday accused 36-year-old policeman Iskandar Rahmat, on trial for the Kovan double murder, of killing a father and son to silence them so that they could not identify him.

Iskandar had testified on Oct 30 that he had wanted to steal from car workshop owner Tan Boon Sin in a bid to resolve his financial woes.

He insisted that his plan was just to grab the money and run, but the ploy went wrong when his 67-year- old victim wised up to the ruse and attacked him with a knife.

But Deputy Public Prosecutor Lau Wing Yum, cross-examining Iskandar on the seventh day of the trial yesterday, put it to him that he had armed himself with a knife, intending to kill Mr Tan "right from the outset".

The DPP also alleged that Iskandar had killed Mr Tan's son, Chee Heong, to silence him when the 42-year-old arrived at his father's Hillside Drive house.

Iskandar flatly denied the allegations. He remained stony-faced and composed as the DPP sought to poke holes in his account.

DPP Lau pointed out that if Iskandar had simply run off with the money as he claimed to have planned, leaving Mr Tan Boon Sin alive, the elderly victim would have made a police report and identified him.

Iskandar replied that he had called Mr Tan from a payphone and worn sunglasses when he met him, and that Mr Tan, being elderly, would not have been able to pick him out in an identification parade.

He disagreed with DPP Lau that, as an experienced investigator, he knew that investigations would lead to his identification.

The court had heard earlier that Iskandar was the initial investigating officer when Mr Tan made a police report in November 2012 about $35,000 stolen from his safe deposit box at Certis Cisco. But the two never met.

On July 10, 2013, facing imminent bankruptcy and possible dismissal from the police force, Iskandar set in motion a plan to steal from Mr Tan, who had $200,000 left in the box.

Posing as an intelligence officer on a sting operation to catch the safe-deposit-box thief, Iskandar told Mr Tan to substitute the valuables in the box with a closed-circuit television camera.

The camera which Iskandar supplied was a $10 fake that did not come with a cover for the battery compartment or any batteries.

The dummy camera was the focus of a good part of DPP Lau's questioning yesterday.

The significance of the issue lies in Iskandar's claim that after he followed Mr Tan back to his house, the elderly man came at him with a knife, accusing the cop of cheating him as there were no batteries in the camera. DPP Lau sought to disparage this account.

Surveillance footage at the Certis Cisco vault was played in court. It showed Mr Tan putting the camera in his deposit box and then taking it out two minutes later. DPP Lau suggested that by this time, Mr Tan would have known that the battery compartment was empty. Iskandar replied that he would not know.

DPP Lau suggested that Mr Tan had left the building to ask Iskandar about the lack of batteries but was assured that it could operate without batteries - that was why Mr Tan later made a second trip to Certis Cisco to put the camera in again. Iskandar disagreed.

The DPP said there was no reason Mr Tan would suddenly become suspicious of Iskandar in the house, after allowing the cop to escort him home and offering him a drink.

Iskandar replied: "I wouldn't know what's going on in his mind."

The trial resumes tomorrow.