A Hong Kong man accused of raping his teenage daughter has been jailed for 6½ years for perverting the course of justice in the lead-up to his trial and during the hearing.

His wife was jailed for three years and nine months for helping him take their daughter away to mainland China just days before he was due to stand trial in October 2018, while his mother and brother were each jailed for four years and nine months for conspiring with him to unlawfully interfere with the girl’s evidence when she finally testified the following January.

Mr Justice Alex Lee Wan-tang said on Monday the case was appalling and one of the rarest of its kind, with four of the girl’s closest family members ganging up on her, leaving the then 15-year-old isolated and helpless.

The judge also slammed the four for having no regard for the law, noting the case was not the result of a momentary lapse of judgment but continuous planning, with the father as the mastermind.

Lee said he did not speculate whether the father had sexually assaulted his daughter, but considered the gravity of those allegations and the fact that the parent did whatever it took to secure his acquittal without showing remorse for his selfish and heinous behaviour.

As for the mother, Lee noted that she had the heart to protect the girl – she had accompanied her daughter to the police station and assisted in the arrest of her husband – but was easily influenced by the man into playing an indispensable role in the incident.

“The court has a duty to send a clear message to the public that perverting the course of justice is a very serious offence,” Lee said. “A defendant must be severely punished even if his motive was to help a family member.”

The judge also appealed to the Social Welfare Department to follow up on the girl’s situation and provide suitable assistance, noting that she had been diagnosed with depression since March 2019 and would age out of her girls’ home in a few months.

Perverting the course of justice is a common law offence. The maximum sentence was capped at seven years until the Legislative Council amended the Criminal Procedure Ordinance in 2008, allowing judges to impose any jail term or fine at their own discretion when the case is heard at the Court of First Instance.

The girl’s 45-year-old father and 42-year-old mother previously pleaded not guilty to one count of carrying out an act tending and intended to pervert the course of public justice. Her father, 40-year-old uncle, 65-year-old grandfather and 67-year-old grandmother have denied another count of conspiring to pervert the course of public justice.

The sentencing hearing came a week after a High Court jury returned the unanimous verdicts against the four family members, while acquitting the girl’s grandfather.

None of the defendants can be named following a gag order aimed at protecting the girl, who was identified only as X in court.

In mitigation, the father urged the court to ignore the allegations of sexual assault and appealed for a shorter sentence so that he could take care of his eight-year-old son upon his release.

Meanwhile, the mother said she wanted to protect her daughter but faced a difficult choice in this unfortunate incident.

The court previously heard that the Shenzhen-born girl filed a complaint when she was 13 in October 2017, accusing her father of sexual assault.

The father was charged and remanded in custody pending trial on two counts of rape and five of indecent assault, with proceedings set to begin in the High Court on October 25, 2018.

Both the girl and her mother were summoned as prosecution witnesses, but neither showed up to take the stand.

A warrant was issued for the mother’s arrest and she was intercepted upon returning to the city with X via the Lok Ma Chau checkpoint on November 4.

The mother was brought to court the next day, during which she explained that she had left Hong Kong because she wanted to protect the family and did not want to see the scandal in the news.

When the girl finally testified on January 21, 2019, she agreed under cross-examination by her father’s defence counsel that he did not rape or indecently assault her. She also agreed with suggestions that she had fabricated evidence in a pre-recorded video interview.

The judge in that trial subsequently ruled that the father had no case to answer, directed the jury to acquit him of all charges and released him.

A case officer, however, had noticed the girl was shaking her head and behaving strangely during her testimony, and interviewed her again.

Police subsequently gathered visitation logs and seized recordings from the reception centre and found cryptic conversations between the father and his wife, brother and parents during visits.

For instance, on October 20, the father instructed his wife “not to come back” from the mainland until after his release.

She left for Shenzhen that afternoon with their daughter and son in tow.

The parents were arrested on January 23, 2019, followed by the grandmother, uncle and grandfather.

The girl later testified that her grandmother and uncle had coached her to play dumb and make a bad impression on the judge in the original case by wearing heavy make-up and skimpy clothes.