The man has interim name suppression.
Crown prosecutor Shawn McManus said the man and his wife became approved Cyfs caregivers in 1989 and many children passed through the homes they ran over 25 years.
The trial concerns the alleged abuse of one girl aged 14 when she was placed in the home with the man in Otago in 1995 for several weeks.
The Crown alleges he went into the bathroom while she was showering or into the bedroom, touching, kissing, penetrating her with his finger, or raping her.
McManus said the girl would tell the trial that the man warned her after one rape that she should not tell anyone what had happened because no one would believe her because he was an approved caregiver and she was a person in Cyf's care because of her bad behaviour.
Years later, police had several recorded conversations with the woman but she did not want to talk about her experience during the placement. The recordings will be played at the trial.
She told police that when she once told Cyfs about it, they told her she was lying and they would not remove her from the address. She said another time, Cyfs told her the man was an approved caregiver and she was a child of Cyfs, and "who would believe you?"
It was not until 2018, when the police made contact again, that she made a statement about the abuse she said had taken place.
Defence counsel Anselm Williams urged the jury to take an objective approach as they listened to the evidence. They should consider whether the complainant was believable and whether her evidence was consistent and supported by other evidence.
The trial is continuing.