[Reporter] Officials in the Los Angeles suburb of Arcadia have taken custody of a 13-year-old girl and they say was kept in such isolation by her parents that she never even learned to talk. The girl still wore diapers and was uttering infantile noises when a social worker discovered the case two weeks ago. But the authorities are hoping she still may have a normal learning capacity. [Narrator] Among the first to see the child was Temple City Detective, Sergeant Frank Linley. [Linley] I already knew that the child was 13 1/2 years old. And I took one look at her and she wasn't much bigger than my daughter, Beverly, who had just turned seven about three months earlier. And I really had a hard time conceiving of the idea that the child was the age that she was. The child obviously had been severely mistreated as she was still in diapers, couldn't walk, she had no verbal skills at all at that point. The last time I was on this street was probably 30 years ago. Yep, there it is. Hasn't changed much. The back yard looks the same. It's all weeds and dead grass. Looks the same as it did in 1970. [Narrator] The house belonged to Clark Wiley. A loner, Clark had turned his back on the world after his mother had been killed in a hit and run accident. After the accident, things in the Wiley house would never be the same again. [Linley] The house was completely dark. All the blinds were drawn and there were no toys, no clothes, nothing that would ever indicate to you that a child of any age lived there. The child's bedroom was back in this corner. That was the bedroom. The windows were covered to about three inches from the top. Which were the only natural light that had ever come in there in all the time the child was in the bedroom. Entire furnishings of the bedroom consists of a cage with a pull down chicken wire lid and some type of piece of wire securing it when they closed it down. There was a potty chair with some kind of homemade strapping device. [Narrator] For 13 years, Genie had spent her nights locked in bed. Her days, strapped to a potty chair. During that time Clark had ordered his son John and wife Irene, never to talk to her. In her darkened room, she had led a life of near total isolation. Even close neighbors were completely unaware of her presence. [Laicans] We came home from work and the police was here and they came to question us. That's when we found out, you know, what happened and, you know, that they had a little girl. Nobody knew, nobody knew before. And when we found out what happened and how she was treated, I mean, everybody was shocked and just unbelievable. [Narrator] For their whole marriage, Clark had imposed his will on Irene. And blind with cataracts, she had been too scared to resist. But one day something broke. While Clark was out buying groceries, she seized her chance and fled. It was the first glimpse the world would have of Clark and Irene's dark secret. [Linley] I met Clark and Irene at Temple City Sheriff's Station. They were both under arrest at the time. When we interviewed Irene she would make no mention of the family whatsoever, particularly the children. I attempted along with my partner to interview Clark. He refused to talk to us. He wouldn't say a word. He never even acknowledged that he understood what we were talking about. [Woman] Mr. Wiley? [Wiley] Yes. [Woman] Why did you keep your daughter in a room-- [Man] Mr. Wiley has no comment. [Wiley] No comment. [Man] We haven't had time to discuss the charge and we haven't even seen them. [Narrator] Unable to face the truth, Clark took matters into his own hands. [Reporter] This morning the authorities reported that 70 year old Clark Wiley shot and killed himself just before he was to go to court and be arraigned for child abuse. [Narrator] After 13 years, Genie was at last free. And for scientists, she was just the case they had been waiting for. For 13 years Genie had lived a life of complete isolation. Raised in a city bedroom, Genie was as much a feral child as if she had been brought up by wolves. At 13 she was the size of a six year old. Worst of all she had never been taught to speak. The question now, could she ever learn? Genie's case was so scientifically important that the government funded a team of scientists to help answer the many questions she posed. Two of the scientists who would become especially important to Genie were child psychologist James Kent and linguist Susan Curtiss. [Curtiss] It's so wonderful to see you. God. [Narrator] Neither had ever encountered a case as extreme as Genie's. [Kent] We looked at her as a-- as a newborn in a way. Even though we know she hadn't-- she came with 13 years of memories and experiences. Not all of them wonderful. Most of them not, I think. And so we felt we needed to start to expose her to what the world was going to be like for her outside the hospital bed. [Narrator] To Genie, everything was a new experience. [Kent] We did what you would do with-- with your own kids. If you were introducing them to the world. You'd take them out and hold them up and show them. Sort of judge from how they reacted to whether this was too much or not enough and you could move on and do the next thing. [Narrator] Genie was making amazing progress. As the experts looked on, they realized that she might be the answer to the question that had troubled science for so long. [Curtiss] So we seized this wonderful opportunity that she provided us in as loving a way as we could but using it to finally get our chance to address head-on specific hypotheses and notions about human language and the human mind. [Narrator] These hypotheses were based on the latest ideas about how children's brains developed. According to the theory, young children could only learn certain things at certain times, called critical periods. Language was one of these critical periods and according to the theory, Genie who was now a teenager, had missed her chance forever. But incredibly, Genie seemed to be proving the theory wrong. As this footage shows, Genie was blossoming. Not only was she delighted by the world around her but she was learning the words for the new things she was seeing. [Curtiss] She was extremely interested in everything around her. She wanted to know the word for everything around her. She wanted to engage people all around her. She was not mentally deficient. Her lights were on and everyone who worked with her from teachers to therapists to me, knew that she was not retarded. It was clear as day. And as she began to learn more and more words, hundreds of words, much more rapidly than I ever imagined. And string them together, I began to think maybe I will be wrong. Maybe she will be the one that will prove that this hypothesis is incorrect. [Narrator] But Genie could not escape the effects of her past so easily. She was still haunted by her traumatic upbringing. Trapped by the memories of the awful fate she had suffered. And linguistically, she had stopped making progress. [Curtiss] She learned tons of words. She has an enormous vocabulary. But language is not words. Language is grammar. Language is sentences. How do you make a sentence? What can be a sentence? What is a sentence? How do you automatically know something's a sentence? So it wasn't because she was cognitively deficient in other respects, it was because she was cognitively deficient in this island of human mind. The mental faculty that we call grammar. [Narrator] At the time Genie was found, brain science was in its infancy. But today we have a much clearer picture of what actually happens in cases of extreme neglect, like Genie's. [Perry] In Genie's brain, the left part of her brain, her cortex, that has those neural systems responsible for speech and language. Because she never heard any words and because she was never taught-- spoken to very often. They didn't get stimulated. And because they weren't stimulated, they got smaller and less functional and disconnected and ultimately that part of the brain literally physically changes. [Narrator] Today with modern imaging technology, we can actually see what happens in the brains of feral children. And the effects are shocking. Without normal stimulation, their brains are smaller and malformed. And the earlier this neglect begins and the longer it carries on, the worse the damage will be. Starved of stimulation, Genie's brain had simply not developed the capacity for language. And now that she was a teenager, she would never be able to learn. Despite this, Genie continued to be a close part of everyone's life. But, there was more trouble ahead. [Kent] Children have to belong to somebody when they grow up and she was still a child. And she needed a family to belong to. So that's what we would have liked, a family that she could belong to. And that's not what happened unfortunately. What did happen is about the worst outcome I think we would have envisioned. [Narrator] On her 18th birthday, Genie moved back with her mother, Irene, into the house in which she had been so terribly abused. But after only a few weeks, it was clear that Irene couldn't cope. From here, Genie was moved into state care with terrible consequences. [Curtiss] I was a student and people wouldn't listen to me. People who needed to intervene did not listen to me. And so I spent lots and lots of time on the phone pleading with people to intervene and save this person, who had had the worst experience of deprivation and isolation in all recorded medical history. [Narrator] Genie moved from home to home. Sometimes with the very people who served as her therapists. This potential conflict of interest raised tensions among the many people involved in her life. And a tug of war erupted over the child. As Genie's condition deteriorated, Irene decided that Susan Curtiss and the other academics had become too close to Genie. A lawsuit followed. [Curtiss] I went from being asked to be her guardian, to one week later being prevented from seeing her or phoning her. And ever since then I've been prevented from having any contact at all. So although I have lots of, you know, I'm still a scientist, I'm still interested in knowing things about her language now. And all kinds of interesting things I would like to pursue academically, primarily, I would just like to see her. [Narrator] Now a ward of the court, Genie lives in an adult care home somewhere in Los Angeles, prevented from seeing the people who once meant so much to her.