A young Perth girl told police her father stayed in the room while she was sexually abused by strangers because he was making sure she was "OK" and "calming her down."

The 13-year-old made the comments in an interview in April 2015, as part of a police investigation into allegations she had been abused by her father and about half a dozen other men, in what came to be known as the "evil eight" paedophile ring.

The girl's interview was played in the District Court at the start of the trial of Alfred Impicciatore, who has pleaded not guilty to four child sex offences — alleged to have been committed when he went to the girl's northern suburbs home in March 2015.

Mr Impicciatore is the only one of the so-called paedophile ring to defend the charges against him and his trial is being heard by a judge sitting without a jury.

The other men, including the girl's father, pleaded guilty — meaning the girl's account of what happened, in her own words, has never been aired publicly before.

The father was sentenced to 22-and-a-half years' jail, while the others received terms ranging from three years to almost 13 years.

In a quiet, and at times hesitant, voice, the girl told a police officer she had sex with a "chubby man" with a "round face" who came to her house on a Friday night.

She said she thought he was a bouncer, and he told her he owned small black dog.

Abuser used blackmail: victim

She said her father stayed in the room during the encounter, to calm her down and make sure she was OK and that the man was not too rough or violent.

However, she did not tell police her father also participated in the alleged abuse, which prosecutor Justin Whalley said was the result of her being a "hopelessly conflicted child", who had been abused by several men.

The girl also talked about being abused by a second man, who she said would give her "spiritual massages".

She said that man would also give her something to sniff that he got from the chemist and would calm her down.

Her father had told her that the man, who called himself "Joe Black" but also went by the name "David", had started threatening that if father and daughter did not do what he wanted — including both of them being blindfolded — he would go to the police.

In November 2015, Dawid Volmer, a former Christian Pastor, was sentenced to more than 10 years' jail for 12 offences against the girl.

His sentencing hearing was told he had had sexual encounters with the girl after he and her father lied to her that the father was being blackmailed by Volmer.

On Tuesday state prosecutor Justin Whalley said the charges against Mr Impicciatore were largely based on "admissions" he made to police when he was interviewed in May 2015.

Mr Whalley also said forensic tests had been carried out on a condom packet discovered in a bedside drawer at the girl's house, and a DNA sample found on it could be linked to the accused.

In a video recorded interview with police played to the court, Mr Impicciatore admitted he had sex with the girl, but said her father had told him she was 17.