(CNN) "I never saw it coming," said Susan, whose family requested that we not use their last names.

In 2008, her daughter's cancer came back for the third time. Hope was in her early 30s. They cried together visiting the funeral home, as Hope decided which kind of flowers she wanted at her own memorial. She wanted doves to be released.

Meanwhile, Hope's doctor couldn't find any past records of her cancer, a bone cancer known as Ewing's sarcoma. He asked Susan for the names of the doctors who had treated her over the past eight years.

Susan went through Hope's drawers and cabinets. Empty.

"There had to be another explanation for why I couldn't find this stuff," Susan told CNN. Her family's story was first reported by the Fort Worth Star-Telegram.

She asked Hope's then-husband, Fabian, for their insurance information to check the medical claims.

"I couldn't find charges on Hope. I'm not seeing CAT scans. I'm not seeing MRIs. I'm not seeing oncology visits," Susan said.

"That was the moment our whole lives changed."

Questioning everything

The next day, she went to the hospital early to meet with Hope's doctor. She had a hunch about what was going on.

"I believe she may have Munchausen's," Susan told the doctor.

Hope threw elaborate parties when she claimed to have beaten cancer. One involved skydiving.

People with Munchausen syndrome will fake illnesses or make themselves sick to get medical care and capture the sympathy of others. They invent their illnesses to seek attention, not for financial or material gain.

When Susan confronted her daughter in the hospital, Hope nodded in confession.

"I was aware of the disorder; I'd just never seen it," Susan said.

The past eight years had been a lie. The parties they threw after Hope beat cancer, the balloons and the band, were all lies. The tattoo across Hope's back -- the wings she'd earned -- was a lie.

Susan wondered what else had been a lie.

"You really start to question everything you've been told. Every single thing you've been told," Susan said. "That includes medical conditions that surrounded my grandchildren. Then you start to wonder if any of that's true, too."

Another revelation

By that time, Hope and Fabian's youngest daughter had been treated for cystic fibrosis for about four years. Early photos show a smiling, cheerful girl with tubes of oxygen under her nose. Her parents adored her.

Hope's youngest daughter was treated for cystic fibrosis for years.

Cystic fibrosis is a genetic disease that thickens mucus in the lungs and other organs. It can lead to breathing problems, infections and, ultimately, an early death.

Hope had been an active participant in cystic fibrosis message boards, Susan said. She was on committees at the hospital and took part in fundraising campaigns. To some, she was a paragon of devoted motherhood.

After Hope's own battle with cancer unraveled, her daughter was brought in to be retested for cystic fibrosis. The test measures the amount of chloride in the sweat, which is abnormal in people with the disease.

During the test, Hope tried to interfere. She began tampering with the bandage, but a nurse and a child life specialist blocked her, according to investigator Michael Weber with the Tarrant County District Attorney's Office, who took on Hope's case.

The test came back negative. Hope's daughter did not have cystic fibrosis.

Weber interviewed the child life specialist who was there. She had accompanied Hope and her daughter to a number of procedures, and "Hope had never cried." But that day, she cried.

"The child life specialist felt that the tears Hope were crying was for herself," Weber said.

Playing the part

What Hope did goes by several names, the most common being Munchausen syndrome by proxy or medical child abuse. Many experts use them interchangeably, toeing a controversial line between a psychiatric diagnosis and an act of premeditated violence.

Munchausen by proxy parents will fake, exaggerate or even cause illnesses in their children. Children, often very young, will typically come to a doctor with a laundry list of medical problems that involve many organs.

Investigators found that Hope infected her daughter with harmful bacteria, which she obtained through her job in a laboratory. They also suspected that Hope removed blood from her daughter so that she would become anemic. On one occasion, Hope's false medical history led doctors to give her daughter an anemia treatment, which sent her into anaphylactic shock, Weber said. Doctors were able to stabilize her.

"These moms are desperate to maintain their role as the desperate, knowledgeable parent," said Catherine Ayoub , a forensic psychologist at Harvard Medical School.

Ayoub has worked on cases similar to Hope's, and she has trained law enforcement to identify the patterns of what she calls "disorders of deception."

"It's not a psychiatric disorder," said Dr. Jayme Coffman , a child abuse pediatrician at Cook Children's Hospital in Fort Worth, Texas. Coffman was involved in evaluating Hope's case.

"They're not crazy. They know what they're doing," she said. "And we don't accept that from any other type of abuse, so why do we want to excuse it?"

The American Psychiatric Association's diagnostic manual does, however, include a diagnosis of "factitious disorder imposed on another." There is little consensus on how to characterize it, with both mental health and pediatric doctors laying claim to the diagnosis.

Some parents keep up the act for years, hopping from one doctor to another and extensively researching diseases to convince doctors and family members that their child is truly sick. It used to be that many of the parents had some sort of medical knowledge or even worked in the medical field, Coffman said.

"But what we're finding now, because of the internet, is they really don't have to have as much prior medical training ... to fabricate those symptoms," she said.

The internet -- and social media in particular -- has also given perpetrators a new outlet for seeking attention and validation, experts say. Some stories have even caught the eye of celebrities, who visit what they believe to be a terminally ill child.

Nearly all known perpetrators are women -- moms like Hope. And many have fabricated their own illnesses, Ayoub said, just like Hope.

But few confess like she did.

A jaundiced eye

"I lied about that to get attention," Hope told CNN, wearing a white jumpsuit in the visitation area of a women's prison in Gatesville, Texas, where she has been since 2010 after pleading guilty to child abuse charges. Her children now live with her ex-husband.

Hope claims that she has a hard time remembering what she did to her family. "Some of it, I'm sure, I've blocked out," she said. She also claims that a diabetic coma was partly responsible for her foggy recollection.

This is a pattern among mothers who confess, said Dr. Marc Feldman , a clinical professor of psychiatry at the University of Alabama-Tuscaloosa, a way of admitting what they did without fully admitting their guilt.

"It clashes with everything that we think we know about motherhood," Feldman said. "It's not just wrong to medically abuse a child, but it's immoral.

"I have to admit I approach those kinds of confessions with a jaundiced eye."

A lot of planning goes into duping doctors and keeping a child sick, Feldman said. Some moms have been caught checking hospital rooms for cameras or looking through doorways to make sure nobody was coming, he added.

"It's hard to believe that they lapsed into some unknowing state of being," he said.

Still, confessions are exceedingly rare. Ayoub has seen fewer confessions in her career than she can count on one hand, she said. Many mothers continue to deceive.

Despite her confession, Hope said, she still lies about "all kinds of stuff." She claims to be deaf, even though she responds to questions when she can't see the speaker's lips.

"Sure, I've lied today," Hope said. "You shouldn't believe anything I'm saying."

Hope, who pled guilty to charges of child abuse, had three children with her ex-husband.

Shadow of a doubt

It is difficult to say how common -- or uncommon -- Munchausen by proxy is. How it gets reported varies from place to place, and some cases are lumped in with other forms of child abuse, according to Maxine Eichner , a law professor at University of North Carolina at Chapel Hill who has researched medical child abuse from a legal perspective.

Eichner has written about how she believes the diagnosis of medical child abuse may mistake some parents of medically complex children for abusive parents. Eichner herself has been accused by a doctor of "overmedicalizing" her own daughter, who had a constellation of symptoms that for years doctors couldn't diagnose, she said. She was not accused of Munchausen by proxy behavior.

"We had an eight-year journey to get my daughter diagnosed" with mitochondrial disease , a type of rare disease that can cause a variety of puzzling symptoms.

Had she and her husband not been well-known lawyers in their community, she said, she wonders whether someone might have made an accusation of Munchausen by proxy. Through rare disease advocacy organizations, she has contacted similar parents who had faced those accusations.

"The folks that I have talked to -- and I have talked to many -- tell similar stories, but with different endings than us," Eichner said. "I went through this period of time when I woke up thinking about them.

"Nobody disputes that this kind of behavior occurs," she said, but without more research on the Munchausen diagnoses, it's difficult to know how often Munchausen is misdiagnosed, as well.

Feldman has pored over countless pages of medical records before testifying in cases -- some in which he believed abuse had occurred and some in which he believed the mother had been falsely accused. Still, he believes the latter happens very rarely.

"Like a jigsaw puzzle, it all comes together," Feldman said, adding that he spends a great deal of time on each case he takes. He said this may differ from doctors, like some pediatricians or emergency physicians, whose duty it is to report something suspicious to child protective services, which the doctors may or may not have time to thoroughly investigate.

Hope claimed that she had stage 4 cancer, but her family found no evidence that that had ever happened.

"It's one of those diseases du jour," Feldman said. "Some people get overexcited when they encounter it."

Even so, he said, the idea of false positives is "overstated."

"You don't want to falsely accuse somebody," Coffman said. "We do have parents that are just super anxious, who come in for every sniffle.

"They're not fabricating symptoms in their child or lying about the symptoms. They're just very anxious parents," she added. "That's just a parent that needs more support and education."

Ayoub said that spotting Munchausen by proxy is not a matter of spotting a rare disease or a set of symptoms; it's about looking for a pattern.

Hope's pattern began, but didn't end, with herself: the appointments she wouldn't let Susan accompany her to, the hair and eyebrows she shaved when she told her family she was getting chemo, the tubes that delivered medicine, food and oxygen to her youngest child.

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"We still question things from our past as to what was real and what was not real," Susan said. "Not just the cancer. Other things.

"We have thousands of questions. The only person that could answer those is Hope."

Hope will be released from prison in October 2019. She said the first thing she'll do is try to make peace with her parents, who haven't visited her in years.

Then, she'll try to find her children.