SINGAPORE - A recalcitrant offender was sentenced to 12 years' preventive detention - his third one - on Tuesday (Oct 17) for committing sexual offences against an underage boy with special needs.

Preventive detention, which can last from seven to 20 years, is reserved for recalcitrant offenders. They must serve the full sentence, with no reduction for good behaviour.

Diagnosed paedophile Toon Wai Mun, now 54, was given his first preventive detention in 1996 for drug offences and had to spend nine years behind bars.

In 2006, he was given his second preventive detention and served a 10-year sentence for criminal intimidation and causing hurt.

In spite of this, he committed his latest offences shortly after he was released last year, the court heard.

Toon, a contractor who fixed curtains, pleaded guilty last month to three counts of sexual penetration of a minor and one count of performing an obscene act on a young person.

Six other charges, including two counts each of criminal intimidation and being in possession of a weapon, were taken into consideration during sentencing.

The court heard that the victim's mother was then behind bars for drug offences and the boy, who was 15 at the time, does not know who his biological father is.

As a result, he was sent to a home run by a charitable organisation in February last year. There, he made friends with a 17-year-old boy who was Toon's neighbour.

The victim left the home in July last year to live with his grandmother in Sengkang.

But he left her flat three months later as he did not wish to live there any longer. Court papers did not reveal the reasons behind his decision to do so.

He then approached the 17-year-old boy and asked if he could stay with him in his family's Jalan Bukit Merah flat for a few days.

The older teenager knew that his family would not be happy if he were to invite strangers to their home and told his friend that he could stay with Toon instead.

He also told the victim that Toon had taken in runaways on previous occasions and housed them in his one-room rental flat.

The two teenagers went to Toon's home and he agreed to allow the younger boy to stay with him.

Deputy Public Prosecutor Kavita Uthrapathy said: "During the time that the victim stayed with the accused, the accused would buy him food and give him a daily allowance. (The 17-year-old boy) told the victim that (he) called the accused 'bapak', meaning 'father' in Malay, and the victim also addressed the accused as 'bapak'."

The victim and Toon were in the flat at around 11pm on Nov 4 last year when the boy asked him if he could massage his legs as he had fallen off his bicycle earlier that day.

Toon obliged but became sexually aroused while massaging the youngster.

He then performed a sexual act on the boy and asked the boy to do likewise.

He committed similar offences against the teenager over the next two days, the court heard.

The victim told the 17-year-old boy about his ordeal on Nov 7 last year.

"The victim explained to (his friend) that he did not like engaging in the sexual acts with the accused but he had nowhere to go and had no money and was dependent on the accused for food and shelter," said DPP Kavita.

The older boy took his friend to meet the former's mother and the woman advised the victim to alert the police. The victim called the police hotline that evening and officers arrested Toon soon after.

DPP Kavita added: "The accused told police that even though he had a Vietnamese wife previously and sought sexual relief by engaging female prostitutes, he had sexual feelings for other males and developed these feelings when he was in prison. The accused developed sexual feelings for the victim while the victim was staying at the flat."

On Tuesday, Toon's lawyer, Mr Melvin Loh, who was assigned to the case under the Criminal Legal Aid Scheme, pleaded with District Judge Eddy Tham for an "appropriate length" of preventive detention, saying that his client had expressed desire to change his ways.

For each count of sexual penetration of a minor, offenders can be jailed for up to 10 years and fined.