SINGAPORE — The fact that former police officer Iskandar Rahmat inflicted 12 stab wounds on car workshop owner Tan Boon Sin makes his claim that he was acting in self-defence questionable, a pathologist testified today (Oct 26).

Iskandar, 36, claims he had intended to only rob Mr Tan, 67, but instead got attacked, and in the ensuing struggle, ended up stabbing him. The former police officer also argues that Tan’s son Chee Heong, 42, charged at him after seeing what was happening, and he had stabbed the man in the melee.

But Dr Gilbert Lau, a senior consultant forensic pathologist at the Health Sciences Authority who took the stand in the trial for the July 10, 2013 double killings today, said the defence’s argument “wouldn’t be logical”. “If I were to lend credence to such a hypothesis at all, then it would beg the question why the assailant would stab Tan Boon Sin not once, twice or thrice, but a total of 12 times ... as well as slitting (his) throat. To me, that would seem quite an excessive form of self-defence,” he said.

The orthopaedic doctor that the elder Tan had been seeing for his bad left knee — he suffered from severe osteoarthritis, a degenerative form of arthritis where the cartilage has worn out — also told the court today that it would have been impossible for his patient to attack Iskandar swiftly.

“In severe arthritis, patients walk with a limp, and have severe deformity of the lower leg,” said Dr Kevin Lee, adding that the elder Tan would not have been able to run.

The prosecution’s case is that Iskandar had intended to kill the two men that day, as part of a robbery plan. After the stabbings, Iskandar fled in the older victim’s car, dragging his son’s body under it for nearly a kilometre before it got dislodged outside Kovan MRT Station, prosecutors say.

On the other hand, Iskandar contends that the weapon, a small knife with a serrated blade, had come from the Tans’ home. It was never recovered after he threw it into a canal at East Coast Park.

Today, Dr Lau raised the possibility that two knives could have been used in the attack.

Most of the wounds on the elder Tan’s body could have caused by the small knife, which had a blade measuring about 9cm, said Dr Lau. But two wounds that were 11cm and 13cm deep were likely to have been caused by a knife with a longer blade, he said.

Two other witnesses told the court today what they saw at the three-storey house at Hillside Drive that day.

Domestic helper, Madam Salamah, 28, was doing her chores when she heard three loud cries coming from across the road. She saw the younger Tan staggering out of the house, cupping bloodied hands to his neck.

Shortly after, a man hurried out of the house, looked at the victim, then got into the car and reversed into him.

The caretaker of a house on Hillside Drive said he was in the garden when he heard a loud thump, followed by the sound of a car door closing and an engine starting. Scrambling out of the gate, Mr Anthony Fabian, 56, saw a car reversing quickly with a person’s legs protruding from the bottom of the rear of the car. He called the police as he ran after it, but the car was already some distance away. A man nearby who heard his yelling gave chase on his motorcycle.

The trial continues tomorrow.