He would go upstairs, on the premise that he was saying a prayer with his niece, then sexually abuse her.
Now in her 30s, Karen wasn't understood when she first told her parents what her uncle, Mark Sewell, was doing.
Sewell was also the son of a trusted older member of the local Jehovah's Witnesses congregation, known as an elder.
Christian churches, as well as other religions, have faced claims of child abuse.
But what is striking about the Jehovah's Witnesses is their explicit policy of dealing with abuse in-house.
Because of their practice of following the Bible literally, they insist there must be two witnesses to a crime, often not the case in child abuse cases.
However, in Karen's case a second witness did come forward: Wendy, a family friend and fellow member of the Barry congregation in south Wales. She had been raped by the same man.
When she reported the crime to elders, Wendy was made to describe it in minute detail to a group of older men.
Later, she had to give her account again in the same room as Sewell.
Afterwards, the elders told her that as it was only her account against that of Sewell, nothing more could be done.
This bringing together of the accused and the accuser in a "judicial committee" is a common feature of Jehovah's Witnesses' justice.
Karen, still a teenager at the time, was put through the process.
The elders also ruled that their separate accusations didn't constitute the required two witnesses.
Despite a pattern of predatory sexual behaviour, it took more than two decades to bring Wendy and Karen's abuser to justice.
He is now serving a 14-year prison sentence.
His punishment from the Jehovah's Witnesses? There wasn't one.
Even when the case came to court, the organisation was reluctant to co-operate.
Karen's father, John Viney, who was also an elder in the Barry congregation, says that elders who knew of Sewell's conduct and were asked to give statements or evidence in court did not want to get involved.
In a programme for Radio 4's The Report, we have identified this lack of co-operation in several other similar cases.
Confidential documents from the Watchtower Bible and Tract Society of Britain - the official name for the Jehovah's Witnesses - that we have seen are explicit about the best way to deal with such matters being within the congregation.
Nowhere in the hundreds of pages we have seen are elders told that they must go to the police, even if the perpetrator confesses, unless state or national law makes it mandatory to report such allegations.
The Jehovah's Witnesses' UK leadership declined to talk to us for the programme.
In a statement, they said they were appealing against a recent High Court ruling in the UK that awarded substantial damages against the organisation for failing to protect a child from sexual abuse by a paedophile.
Their statement also insists that the organisation does take child abuse extremely seriously.
Karen Morgan and Wendy are now pursuing a civil claim against the organisation, hoping that further financial penalty may force the leadership of the Jehovah's Witnesses to change its policies.
For both of them, what made it even harder was the sense that belonging to the Jehovah's Witnesses was part of an all-encompassing lifestyle, with members encouraged to socialise and marry within the group.
The organisation has some eight million members around the world, but as Karen found to her cost, those who decide to have a boyfriend or girlfriend who is not a member may find themselves "disfellowshipped" or shunned.
Jehovah's Witnesses are not the only religious organisation to try to deal with allegations of sexual abuse in-house.
For many decades, that was the preferred method of the Roman Catholic Church, which has since reformed its child safeguarding policies following numerous court cases in the US and Europe against priests for the sexual abuse of children.
Other churches have also tightened up their child safeguarding policies, with the Methodist Church conducting its own recent inquiry into abuse allegations dating back to 1950.
That inquiry has led to calls for the Church of England to hold a fresh internal inquiry of its own, separately from the overarching national public inquiry that has just begun, and from the investigation it published in 2010, which critics termed inadequate.
However, it is the more closed religious communities and new religious movements where it remains hardest for the victims of such abuse to speak out and gain access to secular justice, although awareness of the issue is growing.
Only this month, an ultra-Orthodox Jewish scholar from Manchester - who fled to Israel after he was exposed as a paedophile - was jailed for 13 years.
Todros Grynhaus was deported by the Israeli authorities to face justice in the UK, with his conviction for sex offences against girls leading to a change in attitudes in the Haredi Jewish community.
The case prompted the UK's Chief Rabbi, Ephraim Mirvis, to urge members to report child sex abuse.
The court had heard that both women who testified against Grynhaus in the case had been "ostracised" by their community as a result of speaking out about their ordeal.
For young Muslim girls, the price of speaking out about child sexual abuse can also be high, with many reluctant to report such abuse because of the fear that it would bring shame on them and their family.
Sexual and physical abuse at Islamic religious schools, known as madrassas, has also resulted in some prosecutions in recent years, although often victims still hesitate to come forward with such allegations.
Many religious organisations will find themselves being closely scrutinised in the national independent inquiry into child sexual abuse,  chaired by New Zealand judge Lowell Goddard.
The survivors of such abuse hope that the inquiry will prove itself truly independent, and help ensure that abusers will not be able to rely on their own congregations or religious leaders to protect them - whatever their faith.
The Inquiry will investigate a wide range of institutions including:
Local authorities
The police
The Crown Prosecution Service
The Immigration Service
The BBC
The armed forces
Schools
Hospitals
Children's homes
Churches, mosques and other religious organisations
Charities and voluntary organisations
Full details of the inquiry
Caroline Wyatt's investigation will be broadcast in Radio 4's The Report at 20:00 BST on Thursday, 23 July.
From when Karen Morgan was 12, until she was well into her teens, she was sexually abused by her uncle - a ministerial servant with the Jehovah's Witnesses.