Soon after meeting a girl on Facebook, he asked her to be his girlfriend and then to send him pictures of her naked body.
She was just 13 years old. But that did not stop Benjamin Sim Wei Liang from kissing and hugging her and touching her breasts in a taxi in December 2012.
The security officer then dumped her for her younger twin sister, with whom he went on to have sexual relations.
In just two months, he had committed sexual offences against the twins and two more underage girls.
Most of the sex acts occurred in public places such as handicapped toilets, staircase landings, a bus and taxis.
The slim, boyish-looking Sim, 30, was yesterday jailed for 20.5 years and given the maximum 24 strokes of the cane.
He pleaded guilty to a total of eight charges, including three counts of sexually penetrating a minor, two counts of statutory rape and one count each of performing an indecent act on a child and being in possession of a film without a valid licence.
The sexual predator also admitted to one count of procuring an obscene act performed by a child when he asked the older twin to snap nude pictures of herself and send them to him.
Fifteen other charges, including his indecent acts with the older twin, were taken into consideration during sentencing.
Deputy Public Prosecutor (DPP) Zhong Zewei said that Sim had "trawled the Internet for young girls". He met his victims on Facebook.
DPP Zhong added: "Having made contact, he used them to fulfil his sexual needs, without thought to their emotional well-being."
Using the pseudonym "Peter Tan", Sim met the older twin in November 2012.
Later that month, he pressed her to send him naked pictures of herself and she sent him two explicit shots.
DPP Zhong told Justice Tay Yong Kwang that Sim deleted the pictures after viewing them.
The couple met about four times and he bought the girl items including a Samsung mobile phone that cost about $100.
On Nov 15, she told her younger twin about Sim and the latter added him as a friend on Facebook. She also agreed to be his girlfriend.
He broke up with the older twin.
DPP Zhong said that by ditching one girl for her twin, Sim had "in effect been playing the sisters off against each other".
Sim later met the younger twin at Bukit Panjang Plaza, where he sexually penetrated her at a staircase landing.
They met again at Choa Chu Kang MRT station at around 2.30pm on Dec 10 and they took a taxi to his apartment at Euro-Asia Park condominium at Woodleigh Close, near Potong Pasir.
His parents and two brothers were not home and he took her to his bedroom, where he asked her to perform oral sex on him.
He then slipped on a condom and they had sex.
The younger twin also received gifts from Sim, including a Samsung Galaxy mobile phone.
Sometime in late 2012, he came across the Facebook profile of his third victim, who was 13, and befriended her.
DPP Zhong said: "During (their) chats, the accused asked the third victim about her height, weight, waistline and breast size, whether she was still a virgin and whether she wanted to have sex."
Sometime in January 2013, he picked her up from school in a taxi and they went to his condominium.
He took her to a restroom on the first storey and asked her to perform oral sex on him. She went home after that.
Later that month, he again picked her up in a taxi outside her school.
During the trip to his home, he performed oral sex on her on the rear passenger seat. It is not known if the cabby saw the act.
On another occasion, he took her to his bedroom and they had protected sex. Afterwards, he gave her $20 to take a taxi home.
Sim met his fourth victim, an 11-year-old girl, also in late 2012.
A few weeks later, he texted her to ask her to show him pictures of her breasts. She sent two photographs - one of herself and the other of her female cousin.
On Dec 4, she also sent to his mobile phone a video of her caressing herself.
Sim's crimes came to light 11 days later, when the twins' mother found the Samsung Galaxy phone that he had given the younger girl.