On September 9, the parents of Hana Williams, an Ethiopian teenager living in the state of Washington, were convicted of killing her. During the last year of her life, court documents show, she had lost almost 30 pounds as she was beaten, denied food, forced to sleep in a barn, and given cold outdoor showers with a garden hose. Much of the time she was kept barefoot, although she was allowed shoes if there was snow on the ground. Sometimes she was given nothing but a towel to wear. If Williams had been in school, someone might have noticed that she was underdressed and emaciated. But she was homeschooled, and so her parents, fundamentalist Christians in thrall to a harsh disciplinary philosophy, had complete privacy to punish her as they saw fit. She died naked, face down in the mud in their backyard.

Williams is far from the only homeschooled kid to be tortured or murdered in recent years. Exactly how many is hard to say—research on homeschoolers is incredibly spotty, and what exists is mostly done by homeschooling advocates. But Heather Doney and Rachel Coleman, two women who themselves grew up in homeschooling families, have documented dozens of horrific cases on their website, Homeschooling’s Invisible Children, which launched in May. A database of local news stories and official documents, the site is searchable by category, including Fatality, Food Deprivation, Imprisonment, Physical Abuse and Sexual Abuse. Under Sexual Abuse, to take just one of them, Doney and Coleman found almost 70 victims since 2000—and those are just cases that made the papers.

Coleman, an Indiana University Ph.D. student who studies the role of children in the Christian right, does not believe that homeschooling parents are more abusive than others. Some 1.5 million Americans kids are taught at home, and there’s no reason to think that more than a small fraction of them are subject to severe violence. Indeed, Coleman says she wouldn’t even rule out homeschooling her own children. But she argues that because the practice is almost entirely unregulated in much of the country, it can make abusive situations worse, allowing parents to hide their crimes and denying kids access to outside authority. “Homeschooling enables parents to isolate children,” Coleman says. “That can enable them to abuse them.”

April Duvall, 33, is a member of an online support group for women who grew up in fundamentalist homeschooling families. Before her parents stopped sending her to school, she says, her father, a far-right evangelical pastor, worried that he’d get in trouble if he left marks on her after a beating. “My parents were abusive as long as I can remember, but my dad was afraid they would get caught,” Duvall says. Then, in second grade, her mother started teaching her at home, and “my dad stopped being scared that he would get caught.”

Indeed, when kids are homeschooled, it’s easy for the world to forget that they exist. In August, Erica Lynn Parsons, a 15-year-old girl ostensibly being homeschooled in North Carolina by her adoptive parents, was reported missing by her stepbrother; it soon emerged that she hadn’t been seen since 2011. Her birth mother is now calling for an “Erica’s law” that would provide greater oversight of homeschooling.

Right now there’s remarkably little. In 10 states, homeschooling is completely unregulated, and in 15 more, parents only have to notify their school district that their kids will be learning at home. There are no minimum educational standards for teachers, no curriculum review, no testing or monitoring to make sure that any education is taking place at all. Duvall, for example, says she had to teach herself out of textbooks from Bob Jones University. “If I didn’t do it, nobody made me do it,” she says. “I wanted to go to college.” Her two youngest siblings had it even worse. Their mother, Duvall says, “gave them an impossible list of housework tasks they had do before they were allowed to do schoolwork. I think she just didn’t want them to leave home, ever.”

Even in states with more regulation, like North Carolina, required testing is administered by parents, who are responsible for mailing the results to authorities. “The law gives its officials no right to enter homes or to inspect any records besides test scores,” says a state legal summary put out by the Home School Legal Defense Association, the nation’s premier Christian homeschooling organization.

The Home School Legal Defense Association was founded in 1983, just as homeschooling was catching on among an ascendant Christian right. Many in the movement believed that public schools indoctrinated children in godless secularism and saw homeschooling as a way to give their kids an education steeped in biblical values. At first, homeschoolers faced a great deal of official resistance—some states banned homeschooling outright, while others strictly limited it. During the past 30 years, though, HSLDA has successfully fought to eliminate or drastically loosen those regulations.

Meanwhile, the practice has grown rapidly—according to the National Center on Education Statistics, the number of homeschooled kids increased by 74 percent between 1999 and 2007. No one knows how many of these kids come from deeply religious families, but it’s clear that conservative Christians constitute the single largest bloc.

Among the evangelical homeschooling subculture, there’s an assumption that “anyone who is in favor of increased regulation really wants to ban homeschooling,” says Coleman. Any attempt to curtail the authority of parents, no matter how abusive they might be, is treated as a slippery slope. Michael Farris, the founder of HSLDA, even wrote a novel, Anonymous Tip, about an innocent homeschooling family persecuted by corrupt agents of child protective services.

The power of the movement was demonstrated as far back as 1990, when Florida considered a law that would have required the names of homeschooling parents to be run through a child-abuse registry. “Homeschoolers freaked out, opposed the law, and killed it,” Coleman says. Indeed, one Florida homeschooling organization still touts that victory on its website. This sort of lobbying means that in many places, violent parents who keep their kids out of school can rule them unchecked.

In general, such parents fall into two broad categories. Some are simply trying to hide abuse and keep kids wholly under their control, like the Ohio pedophile Kenneth Brandt, who was convicted last year of raping and prostituting his adopted homeschooled sons. In other families, though, the abuse and the homeschooling stem from the same rigid religious ideology.

The parents of Hana Williams, for example, subscribed to the teachings of Michael and Debi Pearl, promoters of an authoritarian, proudly patriarchal variant of Christian fundamentalism that emphasizes a wife’s total submission to her husband and children’s total submission to their parents. The Pearl’s influential book, To Train Up a Child, advocates whipping children with a thin tree branch from the time they’re just a few months old and has sold well over half a million copies. Their followers have been involved in several child killings, including the 2010 murder of 7-year-old Lydia Schatz, whose homeschooling adoptive parents were convicted of beating her to death for mispronouncing a word.

Coleman, 26, who says her own parents were followers of the Pearls, has a few theories as to why many of these cases involve adopted kids. The eldest of 12 children, she and her siblings were accustomed to harsh discipline their entire lives and knew better than to try and rebel. “Because they started with us so young, there weren’t as many long, drawn-out battles of the will,” she says. “We knew that obedience was immediate, complete, and without question.”

Adopted kids, however, don’t have such long training in submission. Further, says Coleman, they don’t have a lifetime of bonding with their parents, which “can tend to be kind of a staying hand.” (The Pearls recognize that love can interfere with their child training, which is why they warn parents not to let crying “cause you to lighten up on the intensity or duration of the spanking.”) Of course, adoptive parents usually love their kids, too, but, especially with older children, the connection isn’t necessarily immediate. Nor is tenderness likely to develop, Coleman says, “if you start out viewing that child as someone that is evil and needs to have their will broken.”

Sometimes in the wake of a homeschooling death, there will be official calls for reform. In 2011 in Florida, the adoptive parents of 10-year-old Nubia Barahona were arrested for her murder, as well as for the horrific abuse of her twin brother, Victor. Afterward, the state convened an expert panel to review how its social-service systems had failed. In their report (PDF), the panelists wrote that school officials had tried to intervene, noting their “diligence as caring professionals.” In 2010, however, the Barahonas began homeschooling, “taking away most of their visibility to outside eyes and increasing the danger that abuse and neglect would go unrecognized. This was further compounded by the lack of formal requirements relating to the monitoring of students being homeschooled.” (The Barhonas are expected to go on trial next year.)

So far, however, regulations haven’t been tightened, and it’s not clear whether the recent killings will change anything. Earlier this year, Pennsylvania state Sen. Andrew Dinniman sponsored new legislation in response to the 2012 deaths of two young homeschooled boys in Philadelphia: 6-year-old Khalil Wime, whose parents were arrested for starving and torturing him to death, and 5-year-old Dashawn Harris, reportedly beaten to death by his mother’s boyfriend for mispronouncing the word “sad” during a homeschooling lesson. He is awaiting trial for first-degree murder.

Under Dinniman’s bill, when families with recent child-abuse complaints start homeschooling, child protective services would have to be notified. The parents wouldn’t necessarily be prohibited from pulling their kids out of school, but there would be an outside risk assessment.

The homeschooling movement reacted with outrage. “Bad Bills Threaten Homeschooling Freedom” said an alert sent out by HSLDA. The organization was indignant that families that had already been investigated for abuse would be investigated a second time “just because they had decided to homeschool their children.” As of now, legislation’s future is unclear. “We have heard some concerns in questions about the bill,” said Dinniman’s legislative director, refusing to speculate on its chances.

Because the Christian homeschooling movement is fairly new, the first generation of homeschooled students is just reaching adulthood and starting to speak out. Eventually, people like Doney, Coleman, and Duvall may organize to counter the lobbying might of the HSLDA. For now, though, homeschooling parents have all the influence. “I wish the homeschooling community admitted that abuse happens a lot,” says Duvall. “People say there are no abused homeschooled kids in their community, but there probably are.” They just don’t have a voice.