It appeared to be the perfect murder - there were no witnesses, and there was not even a body.
Yet, one-time Grand Prix driver Sunny Ang was sentenced to hang for killing his barmaid girlfriend, Ms Jenny Cheok.
One of Singapore's most sensational murder cases, it marked the first time the prosecution had won a case that was based entirely on circumstantial evidence.
Ang was one of the last murderers to be sent to the gallows by a jury; Singapore abolished jury trials in 1969.
This week in 1965, the preliminary inquiry for the case was heard, and the court was told that Ang stood to gain some $400,000 from the death of his girlfriend.
They had met in 1963 at the bar where she worked. She was 22 and he, 24.
Ang came from a middle-class background and had been selected to train as a pilot under a government scholarship programme, but his poor conduct during training cost him that dream.
He took part in the 1961 Grand Prix, but landed in trouble later for killing a pedestrian through negligent driving, and attempted burglary. He was also declared a bankrupt.
Ms Cheok was a single mother of two who had not finished primary school.
On Aug 27, 1963, the couple went on a diving trip near Sisters' Islands and Ms Cheok disappeared.
Her body was never found.
All that was left was a single flipper she had worn, and its heel strap was found to have been severed cleanly at the top and bottom, likely by a knife or razor blade.
An expert witness would tell Ang's trial that the loss of the flipper would have resulted in a diver's loss of equilibrium and affected the person's mobility.
As an inexperienced diver, Ms Cheok would have panicked and drowned in the strong currents.
Ang, a skilled diver, stood to gain from the payouts of insurance policies he had begun buying for her two months before the dive trip.
He also had a will drawn up in which she left her entire estate to his mother.
In one piece of circumstantial evidence, it was revealed that an insurance policy worth about $150,000 had expired on the day before the diving trip, but Ang extended it just three hours before they got on the boat.
When Ms Cheok failed to surface after her dive, Ang did not seem worried and did not enter the water to look for her.
Within 24 hours, he tried to make full insurance claims.
In May 1965, Ang was sentenced to hang after the jury turned in a unanimous guilty verdict.
The prosecution was led by Mr Francis Seow, who went on to become solicitor-general and an opposition politician.
Ang was defended by Mr Punch Coomaraswamy, who later became a high court judge and diplomat.
Ang failed in his appeal and plea for clemency, and was hanged on Feb 6, 1967.
This article was first published on Feb 22, 2015.
Get a copy of The Straits Times or go to straitstimes.com for more stories.