A Christian California couple charged with torturing their children by starving, beating and shackling them are due in court on Friday.

David and Louse Turpin are scheduled to appear in a courtroom in Riverside for a conference about their case.

They have pleaded not guilty to torture and other charges and each is held on 12 million US dollars (£8.6 million) bail.

The couple were arrested in January after their 17-year-old daughter escaped from the family's home in Perris, California, and called emergency services.

Authorities said the home reeked of human waste and evidence of starvation was obvious, with the oldest sibling weighing less than six stone (37kg).

The case drew international media attention and shocked neighbours who said they rarely saw the couple's 13 children outside the home.

Those who saw the children recalled them as skinny, pale and reserved.

Authorities said the abuse had been going on for so long that the children's growth was stunted.

They said the couple shackled the children to furniture as punishment and made them live a nocturnal lifestyle.

Louise Turpin appears in court in Riverside, Calif. in January

David's parents, James and Betty Turpin, told ABC News they were "surprised and shocked" by the allegations and could understand "any of it".

They said that they are considered to be a good Christian family in their community and that added that "God called on them" to have as many children as they did.

The pair also said their grandchildren had "very strict homeschooling," and they would memorise long passages of the Bible, some of them aimed to learn the entire Bible.

David Turpin appears in court in Riverside, Calif. in January

The courtroom conference is expected to focus on date-setting and other procedural issues.

The district attorney's office has drafted an amended complaint but it has yet to be filed in court, officials said.

It was not immediately clear where the children, who range in age from two to 29, are now.

They were taken to hospital immediately after their rescue but since then county authorities have declined to discuss their whereabouts or condition.

Riverside County has obtained a temporary guardianship for the seven adult siblings, who declined to speak to reporters through their lawyers.

"Our clients need time, space, and privacy while they receive services and begin the difficult process of rebuilding their lives," said Caleb Mason, a lawyer for the siblings.

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