SINGAPORE - The presence of a technician's semen on his daughter's shorts was "very persuasive" in proving his guilt, a High Court judge said on Monday (Oct 15) as he convicted the man of raping the girl when she was 14 years old.

The 35-year-old man, who cannot be named to protect his daughter's identity, had claimed trial to two charges of raping his biological daughter in the family flat in Punggol.

During the trial, the girl testified that her father had raped her eight times over two months.

On Nov 19, 2014, she said, he forced his way into the locked common toilet while she was changing and raped her.

The last time he raped her was on the night of Jan 9, 2015. While her mother was out playing mahjong and her two younger siblings were playing games in the master bedroom, her father raped her in her bedroom.

The girl told her then boyfriend and schoolmate about what her father had done. But she was unwilling to go to the police for fear that it would break up her family.

The boy made an appointment for her to see the school counsellor, and the matter was eventually reported to the police on Jan 13, 2015.

That night, the police went to the flat where they seized a pair of shorts the girl had worn. A forensic analysis found his semen on the interior crotch area.

The court heard that the girl's mother and paternal grandparents did not believe her and blamed her for getting her father into trouble. Now 18, she is living with another family.

In court, her father - as well as her mother, who testified for him - depicted her as a "rebellious" girl who fabricated the allegations to gain freedom from them.

However, Deputy Public Prosecutors Winston Man and Chee Ee Ling argued that the girl had no reason to falsely implicate her father and disrupt her life so drastically. This was underscored by her reluctance to report the matter.

Ultimately, the prosecutors said, the forensic evidence was "damning" and the accused could not explain how his semen ended up on her shorts.

Justice Lee Seiu Kin, in his verdict on Monday, noted that this has been a "difficult" case in that the charges are very disturbing as they involve a daughter accusing her biological father of rape.

After scrutinising the evidence, the judge found that the prosecution has proved its case beyond reasonable doubt.

Justice Lee noted that the semen was found in an area of the girl's shorts that was consistent with her version of events.

The judge was also persuaded by the girl's unusually compelling testimony. Her "version of events was given with a level of detail that can only come from a person telling the truth", he said.

He added that her friends and school counsellor corroborated her account of how the offences came to light.

The case was adjourned for sentencing arguments and bail for the accused was increased from $40,000 to $60,000. Each charge of rape carries up to 20 years' jail, and caning or a fine.