The 13 children imprisoned for years by their parents in their squalid Californian home were beaten, shackled, starved and even taunted with food that they were forbidden to eat, a prosecutor said on Thursday.
The victims, ages 2 to 29, were severely malnourished, suffering from muscle wasting and stunted growth. Several had cognitive impairment and nerve damage from extreme and prolonged physical abuse, the prosecutor said.
Each parent faces 94 years to life in prison if convicted on more than two dozen charges including torture, child abuse and false imprisonment in a case that has shocked the nation and prompted calls for greater supervision of home schooling.
The father, David Turpin, 57, is also accused of sexually abusing one of his young daughters. He and his wife, Louise, 49, sat without speaking, dressed in dark clothes during their initial court appearance on Thursday.
The husband hunched over the defence table with his hands in his lap.
Defence attorneys entered not guilty pleas to all the charges.
At a news conference before the proceeding, Riverside County District Attorney Mike Hestrin described what he said was a case of "human depravity."
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The children were denied food, basic hygiene and medical care and were punished for perceived infractions such as washing their hands above the wrist.
He said the victims were chained for weeks or even months at a time, not released even to use the bathroom. They were allowed to shower only once a year.
"The parents would apparently buy food for themselves and not allow the children to eat it," he said.
"They would buy food, including pies, apple pies, pumpkin pies, leave it on the counter, let the children look at it but not eat the food."
As a result of malnourishment, the 12-year-old child was the weight of an average seven-year-old while the oldest, a 29-year-old woman, weighed just 37 kilograms, he said.
The couple was arrested on Sunday in their home in Perris, California, about 113 km east of Los Angeles, after an emaciated teenage daughter climbed out a window and called police.
A sibling who escaped with her got scared and turned back, Mr Hestrin said.
"The 17-year-old victim that escaped had been working on a plan with the siblings to escape this abuse for more than two years," he added.
The father registered the house, where the family lived since 2014, as the private Sandcastle Day School and listed himself as the principal. The children were the only students. Most states, including California, do not monitor or inspect such schools.
The victims told investigators the parents began tying them up years ago as a punishment, first with ropes, Mr Hestrin said. After one escaped, "the defendants eventually began using chains and padlocks to chain up the victims to their beds," he said.
Harsh physical punishment including beatings and strangulation was meted out for transgressions such as washing their hands above the wrists, which the parents considered playing with water, according to the prosecutor.
The children had not been to a doctor in at least four years and none has ever visited a dentist, Mr Hestrin said.
"They were not allowed to have toys although there were many toys found in the house that were in their original package and had never been opened," he said.
The family relocated to Murrieta, California, in 2010, and then moved again to nearby Perris in 2014, with the abuse and neglect intensifying after they arrived on the West Coast, Hestrin said.
Texas Department of Family and Protective Services spokesman Patrick Crimmins said no report was made there of any misconduct involving the Turpins.
During Thursday's brief court hearing, Judge Michael Donner ordered each defendant to remain held on $12 million bail and set the next court date for February 23.
"A case like that sticks with you and haunts you," Mr Hestrin told reporters. "Sometimes in this business you are faced with human depravity, and that’s what we have here."