RIVERSIDE, Calif. (AP) — They were starved and shackled to their beds, sometimes for months. They were beaten and choked. They were given scant medical care, often denied use of a toilet and allowed to shower but once a year. They lived mostly at night, out of sight of neighbors, and knew virtually nothing of the outside world.

And yet, some of the children of David and Louise Turpin hatched an escape plan.

It took two years to carry out but last weekend a 17-year-old girl and her sister climbed out of the window of their Southern California home. The other girl turned back out of fear but the teen persisted and called 911. That act of courage and desperation freed her 12 siblings from a house of horrors that shocked police, a prosecutor said Thursday in announcing criminal charges that could send the parents to prison for life.

Prosecutors laid out horrifying details of the allegations but didn’t offer any theories about the motivation for what they called an escalating climate of brutality that began in Texas and ended in a small, close-knit desert town a couple of hours southeast of Los Angeles.

“The victimization appeared to intensify over time,” Riverside County District Attorney Mike Hestrin said. “What started out as neglect became severe, pervasive, prolonged child abuse.”

When sheriff’s deputies arrived Sunday at the four-bedroom, three-bathroom house on a dead-end street in Perris, they were appalled. They found a 22-year-old chained to a bed and a house that reeked and contained human waste, indicating that the children were prevented from using the toilet, authorities said.

The oldest child, a 29-year-old woman, weighed only 82 pounds and a 12-year-old was the weight of a typical 7-year-old, Hestrin said.

David Turpin, 56, and Louise Turpin, 49, pleaded not guilty Thursday to multiple counts of torture, child abuse, dependent adult abuse and false imprisonment. David Turpin also pleaded not guilty to performing a lewd act on a child under age 14.

They were jailed on $12 million bail each.

Sharon Ontiveros, 63, stopped by the house with her 3-year old granddaughter, who left a stuffed animal with dozens of others on the front walkway.

“Sure, we’re saying we should have known, but behind closed doors you don’t know what’s going on,” she said.

As for the parents, she added: “They deserve no mercy whatsoever.”

Prosecutors say the children range in age from 2 to 29. The torture and false imprisonment charges do not include the 2-year-old, who was not malnourished. All the children’s names begin with the letter J, according to court documents that didn’t provide their full names.

David Turpin had worked as an engineer for both Lockheed Martin and Northrop Grumman. Louise Turpin identified herself as a housewife in a 2011 bankruptcy filing.

The charges include allegations dating to 2010, when the couple moved to Riverside County from outside Fort Worth, Texas.

The abuse began in Texas with the children being tied to beds with ropes and then hog-tied, Hestrin said. When one child was able to wriggle free, the couple began restraining them with chains and padlocks — for up to months at a time, Hestrin said.

While the children were deprived of food, the Turpin parents ate well and even tormented the children by putting apple and pumpkin pies on the kitchen counter, but not letting them have any, Hestrin said.

Similarly, the children were not allowed to play with toys, though many were found throughout the house — in their original packaging.

“This is depraved conduct,” Hestrin said. “It breaks our hearts.”

David Turpin’s father, James, the children’s’ grandfather, said from his home in Princeton, West Virginia, that he did not believe the reports about the abuse.

“I’m going to talk with the children, find out the real story on this as soon as I can get a call through to them,” James Turpin told The Associated Press.

David Turpin’s lawyer, Deputy Public Defender David Macher, had only begun to investigate the allegations but said the case was going to be a challenge.

“It’s a very serious case,” he said. “Our clients are presumed to be innocent, and that is a very important presumption.”

The siblings, who were schooled at home, were rarely seen outside the house, though the parents posted photos of them smiling together at Disneyland and in Las Vegas, where the couple renewed their wedding vows.

In addition to raising them largely in isolation, the parents may have been able to hide the abuse by functioning while other families slept. The children were reared on the graveyard shift, with the family staying up all night and going to bed shortly before dawn, Hestrin said.

One of the only things the children were allowed to do was to write in their journals.

Investigators were combing through hundreds of journals found in the home, Hestrin said. They are expected to provide powerful evidence against the parents.

Louise Anna Turpin, far left, with attorney Jeff Moore, second from left, and her husband David Allen Turpin, listen to attorney, David Macher, as they appear in court for their arraignment in Riverside, Calif., Thursday, Jan. 18, 2018. The parents of 13 siblings who were allegedly held in captivity in their family’s Southern California home were charged Thursday with committing years of torture and abuse that left their children malnourished, undersized and with cognitive impairments. (Frederic J. Brown/Pool Photo via AP)