A protective older sister sacrificed herself to be abused by her mother’s partner to protect her baby sister, a court has heard

An older sister has made the ultimate sacrifice and took on the abuse by her mother’s partner to protect her baby sister, a court has heard.

A protective older sister sacrificed herself to be abused by her mother’s partner to protect her baby sister, a court has heard.

The older sister, who was about 13 at the time, caught the man abusing her sister who was then aged between 13-16 months.

The District Court heard the couple, who cannot be identified, engaged in a series of sexualised “fantasy” chats where they discussed abusing the woman’s other children and having an “incest” child which she would offer up to her partner to be abused.

They also twice discussed killing a child.

A protective older sister has sacrificed herself to abuse to protect her older sister a court has heard. Picture: File.

The couple both pleaded guilty to multiple charges including the aggravated production of child exploitation material, while the man had also pleaded guilty to charges of unlawful sexual intercourse with a person under 14 and sexual abuse of a child.

In a victim impact statement a prosecutor read to the court on her behalf, the older sister said she was left grieving the life she could have had if her mother had not allowed the abuser into their lives.

“You have no right to be called my mother anymore because mother’s protect their children, not put them in danger.

“You could have protected us, but instead you chose a relationship with that monster.”

She told the man that “instead of caring for us as you should have, you used your position of power within our lives to take what you considered to be yours”.

“You stole the innocence of me (and my sister). You took something from us that you can never give back.”

Lucy Boord KC, prosecuting, said the couple had moved to SA about the time the offending began, and the man, 30, had been sentenced interstate for possessing child exploitation material, including images of “very young infants” being abused.

She said the man had “groomed” the eldest daughter, including showing her pornography and threatening to abuse her younger sister if she did not comply. He also engaged in sexualised communication with the girl, beginning when she was about 12, and asked for sexualised images.

“(The eldest daughter) witnesses the offending against her baby sister and offers herself up in her sister’s place in the ultimate act of protection,” Ms Boord said.

She said it had been the older child’s “instinct to protect her baby sister” and had sacrificed herself.

“She was the only one in the house that had that instinct,” Ms Boord said.

She said the man would threaten to again abuse the baby if the older daughter resisted.

The court heard the mother was aware of the abuse but “didn’t do anything about it”.

“Together (the couple) were a very dangerous combination,” Ms Boord said.

Ms Boord also told the court the girls’ mother, 35, had been writing letters to at least six convicted sex offenders while she has been in custody and only stopped last month

The duo will be sentenced next month.