The California teenager who escaped a home where her siblings were found shackled had hatched a plan to flee two years ago, prosecutors say.
The teenager's sibling had initially fled with her but returned to the house after getting scared, Riverside County district attorney Mike Hestrin said.
The parents, David Turpin and Louise Turpin, have pleaded not guilty to the child abuse charges against them.
The couple's 13 children were found severely malnourished, police say.
The children, who are aged between two and 29 and had all been home-schooled, have been treated in hospital since being freed on Monday.
Mr Hestrin said that the couple had allegedly punished their children by tying them up – first using ropes and later chaining them to their beds with padlocks.
He said the alleged punishments would last weeks or months, and intensified over time.
Prosecutors said circumstantial evidence showed the children were not released from their chains to go to the toilet.
Mr Hestrin detailed some of the gruesome allegations against the parents at a news conference on Thursday.
Among the shocking claims:
- The children were accustomed to frequent beatings, including strangulation
- They were only allowed one shower a year
- The children would stay awake all night until going to sleep at four or five in the morning and slept during the day
- They were not allowed to play with any toys but many were found inside the house in their original packaging
- If the children washed their hands above the wrist they were subjected to punishments, allegedly accused of "playing with water"
- The Turpin parents allowed their children to eat only one meal a day but the parents would sometimes buy food, like pumpkin pies, and place it where the children could see it but not eat it
- They have never seen a dentist and haven't visited a doctor in over four years
- The children lack basic knowledge of life, and did not know who a police officer was
The two-year-old was of normal weight but the other children were severely malnourished, authorities said.
The 12-year-old weighed as much as a seven-year-old and the 29-year-old weighed only 82 lbs (37kg).
Though little is known about their education, some of the children were able to read and write. Mr Turpin also registered a private school in their California home, known as Sandcastle Day School.
Police have obtained hundreds of journals, indicating that the children may have been allowed to write.
Before moving to California, the family lived in Texas.
At one point, the parents allegedly lived in a different house from their children and would drop off food from time to time, officials said.
If found guilty of the dozens of charges against them, the couple face 94 years to life in prison, Mr Hestrin added.
Mr Turpin also faces one count of "lewd act on a child under 14 years of age".
The 13 children were found in an emaciated state in their filthy, foul-smelling house, police revealed earlier. Officers had at first thought all the children were minors but later realised some were frail and malnourished adults, they said.
Mr Hestrin said that when officers arrived, three of the couple's children were chained to their beds.
The charges against David and Louise Turpin:
- 12 counts of torture
- 1 count against David Turpin of a lewd act on a child
- 7 counts of abuse against a dependent adult
- 6 counts of child abuse/neglect
- 12 counts of false imprisonment