Police say 13 siblings who were found malnourished, some of them shackled, in a California home were torture victims.
Riverside County Sheriff's office said the mother was "perplexed" when officers came to rescue the siblings, who are aged two to 29.
Investigators said they had had no previous contacts with the couple, David and Louise Turpin.
Their 17-year-old daughter escaped the home in Perris from a window on Sunday and alerted police.
The teenager was so emaciated that officials said she looked just 10 years old.
Investigators said the unnamed girl had called 911 with a de-activated mobile phone.
She showed officers photos of conditions in the suburban property, 59 miles (95km) south-east of Los Angeles.
Police chief Captain Gregg Fellows told a news conference on Tuesday that three of the children were found shackled inside the home during the raid.
"Some of our staff described that there was a very foul smell inside the residence," Capt Fellows said.
"It was extremely dirty and as we reported previously many of the children were malnourished."
Mr Turpin, 57, and Mrs Turpin, 49, have been held on charges of torture and child endangerment.
Bail was set at $9m (£6.5m) each.
Asked to say more about the torture allegation, Capt Fellows said: "If you can imagine being 17 years old and appearing to be a 10 year old, being chained to a bed and being malnourished and injuries associated with that I would call that torture."
He said investigators have found no evidence of sexual abuse or mental illness at this stage, but added the inquiry was just beginning.
"I can't get into the specific details of the conversation, but it seemed that the mother was perplexed as to why we were at that residence," Capt Fellows told reporters.
The Turpins moved into the property in 2014 and apparently schooled their children at home.
Public records show the house is listed in a California education department directory as the location of "Sandcastle Day School", with Mr Turpin named as principal.
It was described in official records as a non-religious and co-ed institution with six students enrolled.
The rescued siblings were taken to local hospitals for treatment.
Mark Uffer, from the Corona Regional Medical Center, told reporters that of the seven adults found, "it's very clear they're suffering malnutrition".
"They are very friendly, very co-operative and they are hopeful that life will get better for them after this event."
Ivan Trahan, a former lawyer for the couple in a 2011 bankruptcy case, told the Los Angeles Times that Mr Turpin had been well paid as an engineer at defence contractor Northrop Grumman.
According to the newspaper, bankruptcy files show Mr Turpin earned more than $140,000 in 2011, but expenses for his large family exceeded his wages by more than $1,000 a month.
Distraught neighbours said that they barely ever saw the family in public, and that they never spoke to nearby residents.
"Why don't we ever see the kids?" neighbour Kimberly Milligan asked.
"In hindsight, we would have never thought this, but there were red flags. You never don't hear or see nine kids."
The children's grandparents said that they had not seen the family for four or five years.
James and Betty Turpin told ABC they were considered a good Christian family in their community and that "God called on them" to have so many children.
The family's Facebook page shows numerous photos and videos of them, apparently happy and smiling. Many posts contain comments from family or friends.
They appear to have renewed their wedding vows several times in recent years, often with their children present.
In a YouTube video, the couple are seen at the Elvis Chapel in Las Vegas.
Repeating after an Elvis impersonator, Mr Turpin tells his wife: "I offer you this ring as a symbol of my love, baby, baby."
The children laugh along with the impersonator, and clap as the couple kisses, reports BBC.