SINGAPORE - The former leader of a youth gang, who was sentenced to 28 years' jail and 24 strokes of the cane last year for raping a teenage girl, started serving his prison term on Wednesday (May 8) after the Court of Appeal dismissed his appeal against conviction.

During his appeal, the lawyer acting for Koh Rong Guang, 26, pointed to inconsistencies in the victim's account, including the number of times she was raped, to argue that the conviction should be overturned.

However, the apex court found that there was corroborating evidence in the form of testimonies of other witnesses, the victim's nude photos sent from Koh's mobile phone, and text messages between Koh and his right-hand man suggesting that he wanted to have sex with her.

Delivering the decision of the three-judge court, Chief Justice Sundaresh Menon said: "No sensible case has been advanced for why the evidence of those witnesses should be rejected. This is all the more so when taken together with the objective evidence."

The court also denied a request by Koh's lawyer, Mr Irving Choh, for his client to defer the start of his sentence so that he can spend a week with his family. Koh was on bail during his trial as well as after he was convicted.

Koh, who is also known as Charles, was the leader of a gang that loitered around Lot One shopping mall in Choa Chu Kang.

He got to know the victim, who was 13 years old at the time, through his right-hand man, Fu Yiming.

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Koh claimed trial to a total of 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.

These arose from incidents that took place between the end of 2013 and early 2014.

In one incident, Koh used a spanner to hit the wall close to the victim's face before sexually assaulting her.

In another, he punched and kicked Fu, who had accompanied the victim to meet him, and threatened them with a brick. After raping the victim, Koh took photos of her and Fu in a sexually explicit pose.

A few months after the sexual assaults, Koh fell out with Fu over a rioting case.

Suspecting that Fu had implicated him, Koh created a picture collage, including the compromising photos, and asked a social media influencer to post it on Facebook.

The victim made a police report on July 5, 2014, relating to the photos, and later on the same day, made a second report alleging rape.

During his trial last year, Koh insisted that he was never alone with the victim and never laid a hand on her. He contended that she had made up the allegations to get back at him for posting the compromising photos.

Koh was convicted by the High Court of 11 charges but acquitted of the first rape charge as the court found there was no corroboration of the victim's account.