Twelve days later, on 5 June 1968, the Ong family received a second phone call from the same caller, and after some negotiations, the ransom was reduced to S$20,000.

One of the last three persons who rented the car, 22-year-old Richard Lai Choon Seng (赖春成 Lài Chūnchéng), a Singaporean electrical firm owner, was questioned by the police.

Out of the trio, 32-year-old Lim Kim Kwee (alias Ah Tee; 林金贵 Lín Jīnguì) and 23-year-old Ho Kee Fatt (alias Ah Aw; 何记发 Hé Jìfā) were arrested in Malaysia by the Royal Malaysia Police and extradited back to Singapore to face charges of murder and kidnapping for ransom.

A fifth man, 29-year-old Chow Sien Cheong (alias Ah Chong; 赵秀昌 Zhào Xìuchāng), was arrested in Singapore.

[9][10][11] On 28 April 1970, both Chow Sien Cheong and Richard Lai were brought to trial for charges of negotiating and possessing the ransom money.

The three defendants - Lee Chor Pet, Lim Kim Kwee and Ho Kee Fatt - pleaded not guilty to the murder charge, which was brought forward by the trial prosecutor K. S. Rajah.

Singh told the court that according to the holes and torn areas on the shirt, it was deduced that the fatal blows were delivered from behind, and that the attack occurred from behind, and it was likely that a screwdriver was used to stab Ong.

Lai, who acted as the driver, testified that he only took part in the plan due to his need for money to discharge the huge financial debts incurred from his electrical firm business.

Lai, who was unaware of the presence of weapons, stated he was shocked at the violence and thought that their only plan was to kidnap rather than killing Ong.

Goh, who took the stand first, stated that she was asked to keep a large amount of money, which Lee passed to his brother Chor Hock for safekeeping.

He claimed that his statements to the police were fabricated by the investigating officer Ong Hean Teik, and therefore put up an alibi defence, stating that he was working overtime at his workplace, an engineering firm.

On the totality of evidence, the judges rejected Lee's "untruthful" account, Lim's alibi defence and Ho's claims of Lee being the sole person responsible for the killing, and they further determined that the trio were responsible for the ruthless and premeditated murder of Ong, who was unfortunate to be a target for kidnapping due to his family's affluent background.

[39] Therefore, in a final bid to escape the gallows, Lee submitted a petition to the President of Singapore Benjamin Sheares for clemency.

[40][41] On the morning of 27 January 1973, the three Ong Beang Leck murderers - 29-year-old Lee Chor Pet, 37-year-old Lim Kim Kwee and 28-year-old Ho Kee Fatt - were hanged at Changi Prison.

At the time when the three men were hanged, the two minor accomplices Richard Lai and Chow Sien Cheong were already released from prison.

Among the cast, Lawrence Wong, a Malaysian actor based in Singapore and later in China, would portray one of the murderers Lee Chor Pet, which was one of his early roles of his career.