After a Connecticut woman was accused of holding her stepson captive for two decades, education advocates said the state’s largely unregulated homeschooling system could allow abusive parents to keep their children from public view with no protective oversight.

The stepson, now 32, told police that he was removed from public school in the fourth grade and that he was homeschooled.

His stepmother, Kimberly Sullivan, was released from jail Thursday after she posted $300,000 bail on charges of imprisoning and starving her stepson.

Her attorney Ioannis Kaloidis said Sullivan denies any wrongdoing.

Waterbury police have not publicly identified the stepson, who they said is 5-feet-9 and weighs 68 pounds. He told police he had been severely abused since age 11, enduring “prolonged abuse, starvation, severe neglect, and inhumane treatment,” they said.

When he was removed from school as a child, a former principal, Tom Pannone, went so far as to knock on the family’s door looking for him, Pannone said in an interview.

Pannone, who was principal of the now-closed Barnard Elementary School in Waterbury, said he was given several explanations about why Sullivan’s son was no longer attending class in the early 2000s, including that he was being homeschooled.

Interim Superintendent Darren Schwartz said, “Based on available information, the student was unenrolled from the Waterbury Public Schools in 2004.”

Waterbury Police Lt. Ryan Bessette told NBC News the stepson told authorities that his formal education ended around the fourth grade and that then he was homeschooled.

Pannone told NBC Connecticut: “You could just simply withdraw your child from school, and you didn’t even have to make a plan for homeschooling. It was a very lax system, and a lot of parents would just say, ‘I’m homeschooling them,’ and that was it.”

Sarah Eagan, of the Center for Children’s vocacy, a legal rights law firm for children, said that many states have some type of policy or regulatory framework around withdrawing children from school for the stated purpose of homeschooling but that Connecticut does not have clear guidelines.

“When a child is dis-enrolled from school, with a caregiver saying, ‘I’m withdrawing my child to home school,’ that kind of ends it. That’s the end. There is no ‘We’ll meet again. We’ll verify,’” Eagan said. “Because Connecticut has no system for that and has been reluctant to create a system yet.”

Eagan, who previously worked at the Office of the Child vocate, a state watchdog agency, said that while parents have a right to educate their children as they see fit, states have a clear legal interest in ensuring the safety and education of their citizens.

Which is why legal challenges to states’ homeschool regulations have been upheld for the most part, she said. 

“It is a balancing of rights and responsibilities, and it needs a thoughtful balance, because most people who are directing the education of their children are likely doing so well and appropriately,” Eagan said.

“But you have individuals who take advantage of the system, and it’s not really about homeschooling. It’s about people who pretend, people who use the pretense of homeschooling as a guise to remove their child from public view.”

The years of cruelty for Sullivan’s stepson ended Feb. 17 when he used a lighter, hand sanitizer and paper to set the fire, he told police.

When authorities found him, he was “extremely emaciated, his hair was matted and unkempt, he was very dirty and his teeth all appeared to be rotten,” according to an arrest affidavit.

“Investigators further discovered that he had been provided with only minimal amounts of food and water, which led to his extremely malnourished condition,” police said.

To remove a student from public school in Connecticut, a parent “should” formally submit that intention to district offices and file papers for the “child’s withdrawal from school,” according to the state.

While parents are told to maintain “a portfolio for each child which contains samples of activities, assignments, projects and assessments, as well as a log of books and materials used,” regulations do not appear to have significant enforcement provisions.

The National Home Education Legal Defense Association ranks Connecticut as among the least-regulated states for parents or guardians to remove their children from class.

Connecticut, Texas and Idaho have “no notice, low regulation” over homeschooling, the association said.

While state officials could ask parents to show them portfolios of their children’s work, the group said that it is “not necessary” and that if “you are asked to participate in an optional portfolio review, please contact us for assistance.”