The incident took place in July 2017 when Tamilarasan, 44, broke into a flat while intoxicated and attacked the maid who was ironing clothes.
Tamilarasan, referred to as a repeat sex offender, had recently been released from a 16-year jail term for previous rape charges.
He was found guilty of four charges, including aggravated sexual assault, house trespass to commit sexual assault, outrage of modesty, and impersonation of a public servant, as reported by Channel News Asia.
The term "preventive detention" is applied to persistent offenders to safeguard the public from potential harm.
Deputy Public Prosecutors Chew Xin Ying and Sheldon Lim advocated for the maximum sentence of 20 years' preventive detention for Tamilarasan due to his history and nature of the crime.
During the sentencing hearing, Tamilarasan's uncle made an emotional appeal for a gag order on his nephew's identity. He argued that he had witnessed remorse from Tamilarasan during his prison visits. As a result of these pleas, Justice Pang Khang Chau ordered an additional report on Tamilarasan's suitability for preventive detention.
The subsequent report confirmed the earlier conclusions, and the prosecution stood by their demand for 20 years of preventive detention for Tamilarasan.
They opposed the defence's request to backdate the sentence to account for the time Tamilarasan spent in remand, asserting that preventive detention differs from remand.
Tamilarasan's uncle, once again, expressed his views during the proceedings. Defence lawyer Foo Ho Chew maintained that the accused was properly represented and that all statements should be communicated through legal channels.
In response to the case, Justice Pang Khang Chau expressed concern over Tamilarasan's lack of remorse and acceptance of responsibility for his actions. The judge labelled him a "menace to the public" and beyond the possibility of redemption.