SINGAPORE - A 34-year-old man was sentenced to 16 years' jail and 18 strokes of the cane on Wednesday (March 14) after the High Court found him guilty of raping and molesting his biological mother.

The man had denied the charges, claiming that his mother, who was 53 years old at the time of the offences on Oct 4, 2013, had conspired with his stepfather to make up the allegations to get him out of their one-room flat.

Judicial Commissioner Foo Chee Hock said the case raised two disturbing questions: whether a mother would falsely and cynically accuse her son of raping her, and whether a son would sexually assault his mother.

The judge found that the prosecution had proved its case beyond a reasonable doubt against the accused on the three charges for rape, aggravated molestation and molestation.

The accused cannot be named to protect the identity of the victim, who is now 58.

The man, who has past convictions for drug consumption, burglary and robbery, is the second of the woman's three sons from her first marriage. Five months before the rape, she invited him to live with her and her second husband as he had no home of his own.

In the early hours of Oct 4, 2013, she was alone sleeping when her son returned and sexually assaulted her.

During his trial in 2016, the former safety coordinator testified that all he did was to lift up her nightdress because he wanted to see her private parts.

But the prosecution argued that this was just a belated concoction to explain away a "damning" audio recording made by his mother, who had phoned him after the rape.

In the six-minute phone conversation between the two in Malay, she repeatedly asked him why he "kacau" (disturb) her. The man, who is known to his family members as Boy, replied that he liked it and wanted it again.

The woman also asked him: "Why you force me in the morning just now?... There are pretty women you can get, why like this?... (I am) your mother you know. How Boy? In this world, can something like this happen?"

Deputy Public Prosecutor Sharmila Sripathy-Shanaz argued that the recording was clear proof that the accused had forced himself on his mother. The victim had testified during the trial that she used the word "kacau" to refer to rape because she was sad and confused at the time.

During sentencing arguments, the DPPsaid the victim "learnt what it meant to be re-victimised when the defence made the outrageous submission that she could have 'shut the gates' by crossing her legs".

"This preposterous submission is premised on the antediluvian notion that a woman can resist a rapist if she really wants to. Your Honour, there is absolutely no room for such statements in the 21st century," said the prosecutor.

The defence, assigned under the Criminal Legal Aid Scheme, had also argued that there was no mention of the word "rape" in the recording. Led by Senior Counsel Harry Elias, the defence also argued that there was a glaring lack of DNA evidence and that no injuries were found on the woman.

A vaginal swab taken from the woman at the Singapore General Hospital was not tested for semen by the Health Sciences Authority because it was placed in a wet tube, which was the wrong medium.

The woman's nightdress tested positive for potential seminal fluids but the sample was too weak for further confirmatory tests.

The defence also pointed out that the woman was calm and collected after the rape and went about her usual routine instead of calling the police or her family.

Summing up the case, the DPP said: "There are no winners in this case - not least the victim who will forever carry the indescribable humiliation, betrayal and hurt so callously inflicted on her by her son on October 4, 2013 and then again in court."