A girl of 12 was repeatedly sexually abused by a man she met on the internet, Belfast Crown Court has heard.
The jury was told that Kevin Catney was 17 when they met.
Catney, from Andersonstown Park Belfast, denies 11 charges, including rape, indecent assault and gross indecency on dates between August 19, 2008 and November 1, 2008.
The court was told that the girl could remember that the first time Catney raped her was on a park bench in Twinbrook.
He allegedly had sex with her in his car and at his parents' house while they were on holiday.
A prosecutor told the seven men and five women jury there was a defence to some charges if Catney had a reasonable belief his alleged victim was over 16.
She added: "We will say that when you have heard the facts you will be aware and will realise there is absolutely no question that he thought she was over 16."
Catney accepted he knew the girl, but claimed he only tried to be her friend and did not touch her sexually in any way.
The trial continues.