When a 17-year-old girl jumped out a window from the house where her parents allegedly starved and tortured their 13 children, she broke a silence that had likely lasted for years - according to a psychiatrist who has analysed the case.
It's not clear why the teenager waited so long to act, but psychiatrists say such behaviour is not uncommon even in cases of extreme deprivation.
Dr Bruce Perry is a psychiatrist who is a senior fellow at the Child Trauma Academy in Houston.
He led a team of therapists that interviewed most of the surviving children from the Branch Davidian cult in Waco, Texas.
Most people would recognise milder forms of the same inaction that is a coping mechanism, whether it's failing to speak out against off-colour jokes, enduring sexual harassment or staying in an awful marriage, Dr Bruce Perry said.
"This happens all the time. The number of individuals who would immediately respond to an opportunity where they could get away is very small compared to the number of people who would have that paralysis and insecurity and confusion about what to do," he continued.
Only after many missed opportunities did the teen probably work up the courage to act, he said.
"It's pretty remarkable that she'd do that... the power that must have been exerted to keep an entire family like that for so long must have been pretty sophisticated."
David Allen Turpin and his wife, Louise Anna Turpin, were arrested on Sunday after authorities found the malnourished children in their home in suburban Perris, 96 kilometres southeast of Los Angeles.
They were jailed on $US9 million bail each and are expected to appear on Thursday in Riverside County Superior Court on charges that could include torture and child endangerment, authorities said.
Some siblings were shackled to furniture in the "foul-smelling" four-bedroom home that looked perfectly normal from the outside.
The couples' children - ages two to 29 - were so emaciated the older ones still looked like children. Authorities thought the 17-year-old daughter who called 911 was only 10 when they found her.
Until the girl fled with photographic evidence, it appears no one, neither neighbours nor public officials, knew anything about what was happening inside.
The Turpins have lived in two Riverside County communities since moving to California in 2011, and police said they were never called to either home, nor were any reports fielded by child protective services.
In Hill County, Texas, where they lived previously, the sheriff's office reported receiving a call from a neighbour complaining a pig that belonged to the Turpins escaped for a pen and ate his dog food.
In another complaint, David Turpin reported that the family's dog had bitten their four-year-old daughter on the face. He told police he took the girl to a hospital for stitches and the dog to a veterinarian to be put down, according to records obtained by The Associated Press.
It's not clear what motivated the Turpins to live a secluded life with their large brood or what went on in the house.
"They develop a kind of cultish doomsday type of religion where the father becomes this mythical leader and the mother and children's duty is to serve the father," Lawyer Ambrosio Rodriguez said, referring to cases of a similar nature.
Mr Rodriguez was a longtime Riverside County prosecutor who sent Jessica Banks, a pastor and mother, to prison for life for beating, starving and drugging her five adopted daughters, who were kept locked in her garage.
The Turpin children appeared to be cut off from the outside world, despite taking a trip to Disneyland and Las Vegas, where the parents renewed wedding vows in a service presided over by an Elvis impersonator.
"They weren't allowed to watch TV. They weren't allowed to have friends over - the normal things that kids do," the children's aunt, Teresa Robinette claimed to NBC.
Individuals held under such conditions often become so physically and emotionally weak "that they are unable to free themselves, even if an opportunity arises," Dr Allen Keller said.
Dr Keller runs the Bellevue-NYU Centre for Survivors of Torture in New York.
"The abuser has basically taken complete control of them. It is a state of severe helplessness."
The children were educated in the home. No state agency regulates or oversees private schools in California, but they are subject to an annual inspection by the state or local fire marshal.
"I've seen this movie before," Mr Rodriguez said.
"It's going to get more creepy and make our skin crawl. And at the end of it, we're all going to be asking the same question: 'How did this happen in front of us and no one noticed?"'
