SINGAPORE - A 25-year-old man went on trial in the High Court on Tuesday (Jan 16) for raping a girl, who was then 13, on four occasions between November 2013 and January 2014.

The girl, who is now 17, made a police report against Koh Rong Guang after a collage of sexually explicit photographs he had taken of her made the rounds on social media.

Koh, who describes himself as self-employed, faces 12 charges - four of statutory rape, one of sexual assault by penetration, three of criminal intimidation, two of committing an indecent act with a young person, one of causing hurt and one of circulating a nude photo of the girl.

He is contesting all the charges and is defended by Mr Irving Choh.

Most of the offences were allegedly committed at the staircase of a karaoke outlet at Choa Chu Kang Centre and the staircase of a block of flats in Choa Chu Kang Crescent.

Setting out their case, deputy public prosecutors David Khoo and Sruthi Boppana said the girl became acquainted with Koh in late 2013 through a friend named Fu Yiming, then 16.

Yiming was part of a group led by Koh that used to hang out at the Lot 1 shopping mall and the adjacent Choa Chu Kang Centre, which they dubbed "Lot 2".

The prosecutors said the girl will testify that in late 2013, Koh accosted her while they were at the karaoke outlet at Choa Chu Kang Centre and proceeded to rape her at the staircase.

A few weeks later, Koh allegedly isolated her again at the staircase and threatened her by using a spanner to hit the wall near her face. Koh allegedly forced her to perform oral sex on him and raped her.

He also allegedly forced her to strip and took a photo of her in the nude, which he sent to Yiming via chat platform WhatsApp.

In the third incident, Koh allegedly raped the girl at the staircase of Block 672A, Choa Chu Kang Crescent. After he was done, Koh allegedly told two other youths in their group, who witnessed the alleged rape, to have sex with her, but they declined.

The fourth incident allegedly took place on Jan 24, 2014, after Koh contacted the girl, asking her to meet him. Fearful of what Koh would do to her, she asked Yiming to go with her.

When they met at the staircase of Block 672A, Koh allegedly threatened them with a brick and began assaulting Yiming.

The girl then followed Koh to another floor, where he allegedly raped her. After the rape, he allegedly made the girl and Yiming pose in a sexually explicit manner and photographed them.

Koh then forwarded a collage, comprising three photos from this incident and a photo identifying the girl, to a friend, telling him to post it on his Facebook page.

The girl started testifying on Tuesday behind closed doors. The trial is scheduled for eight days.

The punishment for statutory rape is between eight and 20 years' jail and at least 12 strokes of the cane.