A 25-year-old man was acquitted yesterday of having unlawful sex with a 13-year-old girl when he was 18.

The man, on trial at Donegal Circuit Court, had pleaded not guilty to a single count of sexually assaulting the girl in his car at a beach car park on a date in October 2003.

He admitted having sex with the young girl but insisted that he believed she was 18 or 19 at the time.

He was the sixth man to face charges of sexually assaulting the girl when she was 12 and 13 and the only one to be acquitted.

The troubled 13-year-old, who kept a detailed diary of her sexual exploits, recorded having sex 57 times with 22 men by the age of 13.

Three men are serving jail sentences while two others have been given suspended jail sentences.

Yesterday it took the jury of seven men and five women just under half-an-hour to return a verdict of not guilty.

The trial had heard that the extremely vulnerable 13-year-old had turned her back on a troubled family life and befriended older teenagers.

In 2003, by the time she was aged 13, she was drinking alcohol, smoking and having sex with boys and men.

She kept a detailed diary in which she recorded the names of men she had sex with as well as colour-coded lists on which she rated the men. One such list contained 55 names.

Capable

The case for the prosecution was not that she had been coerced into sex, but that she was not legally capable of consenting to sex.

In her evidence, the young woman, now aged 20, said she believed the accused man had known her age because he had previously been in a relationship with her 15-year-old friend, and knew that she was younger.

The accused man told the trial that he had met the 13-year-old in a pub where she had purchased alcohol.

He said she dressed older than her age, wearing "stylish clothes" and "big, fancy high-heeled boots".

Judge John O'Hagan told jurors that a mistake about the age of a young person could be raised by the defence.

If the jury concluded that there had been such a mistake, then the defendant must be given the benefit of the doubt.

But if they rejected it, then they must convict.

The judge recalled the defence's case that the girl was not refused admission by pub bouncers and had bought drinks at various bars.

He also pointed out that the victim's mother had been called in evidence just to prove her daughter's age.

"I can only say it as a matter of comment that the mother was not asked in evidence how her daughter looked at the age of 13," he said.

Defence counsel Hugo Hynes said that the law gave the defendant allowance for a genuine mistake and he believed the girl was older than him.

Seconds after the verdict, the woman left the court with her father and social worker.

Irish Independent