A Land Transport Authority security auditor, who used "ItsmeDeedeeYourfrenlyfren" as his Facebook moniker to prey on young boys from mid-2015 to last March, was jailed for 15 years yesterday.

Before handing out the sentence, District Judge Jasvender Kaur said that Soffiyan Hamzah, 38, was a serial offender who had targeted 15 minors in all. She added: "The law exists to protect young persons."

Soffiyan pleaded guilty last month to eight counts of sexual penetration involving minors below 16.

Seven other similar charges and 68 others of commercial sex with boys below 18 were taken into consideration during sentencing.

Four counts of sexual grooming and three charges under the Films Act, including being in possession of 453 obscene films, were also taken into consideration.

Yesterday, Deputy Public Prosecutor Gail Wong told the court that Soffiyan has a propensity to commit paedophilic offences.

She said: "The accused placed all of the victims at risk of harm by exposing them to the risk of transmission of sexually transmitted diseases, as no protection was used for all of the sexual acts."

She added that Soffiyan even instructed one of his victims, then 14, to position himself in "a porn star-like pose". The youngster was then asked to take pictures of his own private parts.

Soffiyan also recorded a video while performing oral sex on another victim, then 17.

DPP Wong stressed that minors are in danger of being targeted by Soffiyan, and added: "Such obscene child pornographic materials allow the victims to be abused again and again, as there is a permanent record of their naked bodies which predators like the accused can view... whenever and wherever they wish."

Soffiyan was known to his victims as "Dee" or "Dee Dee". None of them knew his real name. In his Facebook profile, he said he was gay and would perform oral sex on anyone. He also stated that he would pay, and some of his victims were given $100 after every encounter.

He would usually arrange to meet the boys near MRT stations for what he would describe as his "work". The court heard that most of the sexual encounters took place in a toilet at JCube shopping centre in Jurong.

In January last year, one of his victims, then aged 16, introduced his younger brother, then 15, to Soffiyan. The younger boy met Soffiyan twice.

The case came to light after the boy told his teacher about the encounters. The teacher alerted the police on March 10 last year and Soffiyan was arrested three days later.