? This is what it means ? Gospel singer Natalie grant sings about the loss of a child in "Held." That popular song may have made her the target of an elaborate hoax, one that exploited her best... See More
? This is what it means ? Gospel singer Natalie grant sings about the loss of a child in "Held." That popular song may have made her the target of an elaborate hoax, one that exploited her best intentions. I spoke to who I thought was this little girl that was dying. It gist broke my heart because I began at that point, I think my emotions got the best of me. She loved a song of mine. She asked me to sing to her and was that it. Reporter: She wasn't the only victim. We have heard this story before. For a year and a half "Nightline" has been unraveling a web of deceit, investigating a hoax that snared at least a dozen celebrities, among them Melissa Gilbert, Kate Gosselin and some of the Dallas cowboy cheer leaders. Country music stars, too. Wow. I want to be him. Reporter: The guy behind this country hit about the perils of getting hoodwinked online. Brad paisley. ? I was down pe pizza pit ? Reporter: His number one single "Online" tht video, Jason Alexander plays a sci-fi nerd who passes himself online as the ultra cool paisley. ? I drive a maserati ? Glass of wine -- ? so much fooling online ? The idea of the fantasy world the internet has become. Reporter: You experienced the dark side of that. And the dark side has been there all along. Reporter: Brad and his wife Kimberly williams-paisley had no idea how dark it could get until they were sucked into a cruel and elaborate hoax, a hoax that left Kim paralyzed with fear. Sxw I felt so violated and scared. Reporter: Brad demanding justice zplf it's like emotional terrorism. Reporter: It started with an e-mail sent by a total stranger, one of thousands of e-mails but this stood out, from a mother with her daughter's dying wish. 8 years old and had neuroblastoma and saw a movie of mine called "The Christmas shoe T shoes" saying her daughter found inspiration from that movie. She said her drawaughter beinged her to get in touch with me. It felt real. I would like to talk to her. Reporter: Talk they did by phone, e-mail and text. I heard this hustling and she put this girl on the phone. And she said this is Claire. Thank you for letting me love you and thank you for being my miracle. I remember this instinct in me thinking what if this is a hoax? But it was so quickly trumped by an overwhelming feeling, what if it's not a hoax? I have a chance to help this little girl. Reporter: At the time the paisleys had no way of knowing others had fallen victim to the same hoax. Neither did Natalie grant or anyone else. For a time, they all thought it was real. After one suspicious celebrity tipped off a "Nightline" producer, she realized he wasn't the only one. She started comparing notes with all of the victims and finding in each case, the hoaxer used almost the exact same M.O. I had the e-mail written to the paisleys. "I have an 8-year-old daughter who is suffering from neuroblastoma." One written to a gospel singer named Carmen hope Thomas, stage four neuroblastoma, the exact same thing written to Natalie grant. We confirmed at least a dozen people. And at least a dozen more we're working to confirm. Reporter: Who is in your collection? John Henson, host of "Wipeout." Little big town. Kate Gosselin. Reporter: She dedicated a show? She learned from us it was a hoax. Another producer e-mailed Kate Gosselin when she put two and two together. When I received your e-mail I yell out loud. I said oh, my gosh. Reporter: We're still finding other victims. When she saw our first report on "Nightline," Melissa Gilbert tweeted us and she was a victim. She said how easy it was to get hooked. It was totally plausible. They weren't saying can you send money, weren't saying can you come visit. I just want to talk to you. And then it started to get weird. Jesus loves me this is know. Reporter: Supposedly at death's door the little girl sang this song for Kim and brad got on the phone and sang to her "Amazing grace." You're singing to someone's dying kid. There is no way that's not real. How can that not be real? Reporter: Right when they're hooked, the hammer drops, they get the call they're dreading, Claire is dead. The call came and it was very, very sort of to the point and she just said she's gone. It's parent's worst nightmare. And my wife started bawling. She hit my softest spot. As a mother, you know, wanting my kids to be okay. Hi, it's just care live. Reporter: The calls continued. Got even more outlandish. I also wanted to know if there is a version of your husband singing "Amazing grace" I could use that for the service. Reporter: Check out this message. Detailing plans for the funeral. Oh, and if it was okay to put your picture in the casket like she requested. And I hope you have a really good weekend. And thank you for everything. Bye-bye. Reporter: Almost immediately the story started to unravel. I said where can I send flowers for the funeral? Reporter: She didn't have an address. She said don't, send a donation to your local children's hospital. I had like a physical reaction, every red flag went up. I remember just looking at people around me, who is it? How many people were involved in this scam? And are they right here? Are they watching me right now? Reporter: You were worried they might be a threat to you? Yes. This person was crazy. I watched my wife buckle when she realized this wasn't a real girl. I vowed that night I'm going to find her. I'm going to find her and make sure that this person is not able to do this or isn't capable of doing worse. Reporter: But this deception was bigger than the paisleys even imagined. As "Nightline" dug deeper it became clear the hoaxer was isn't just stalking celebries, she was stalking cancer victims, stealing their photos and stories. We went to meet one family, the Thomases of tiffin, Ohio, their daughter died in 2006 of guess, what neuroblastoma. She had an infectious smile. Reporter: The hoaxer stole a photo off her website. Like she knew my story better than I knew my story. Read my journal entries so many times like she internalized it and when she would call the famous people it was like she convinced herself she really was me. That's the sick et part about this, that's part when I start to talk about that that's when I get really mad that Mr. There were real kids, that there were real photos. Reporter: Ironically, the photos helped unravel the mystery. You pulled the data off some of these pictures? Right. The journal entries were in some ways her undoing because she created them. She didn't lift them from a blog. Reporter: Buried in some digital images, location data from the camera they were taken on. You enter in Google maps it shows a location in Mongolia. Reporter: A dead ent at first. But it's just simply that Mon Mongolia is on the other side the world. If you enter a minus sign you get the actual address. 206 walnut street. Reporter: In Douglas, Wyoming. Hometown of the jackalope a mythical creature used to fool city slickers. Fitting mascot for a hoaxsters. We found her at a koa campground. After eight months of searching, the woman toying with so many people's emotions. We're face to face with hope Jackson, 37-year-old mother of two perfectly healthy kids. You never, god prevent had the experience of losing a child? No. No. I hope I never do. Reporter: You don't think it was incredibly bad karma? Yes. Well -- now looking back, of course. Reporter: We spent a whole day with her. She was contrite. I'm 100% responsible and I have to live with that every day of my life. Reporter: Philosophical. I hopeings some sort of healing, not only the people I hurt but for me as well. Reporter: Showed flashes of anger. All I can do is apologize which I've done. And I can't -- I can't make them like me or forgive me. Reporter: And broke down in tears again and again. Horrible, shameful, I hurt -- wrong. Reporter: We confronted her with an e-mail she wrote Angela Thomas promising she would stop using Christie's picture. I hope to be a better person and mother. I don't expect forgiveness, I just wanted to say how sorry I am and I want use your photos or anyone else's. Thank you for your time. Reporter: You sent that? Uh-huh. Reporter: But it was after you sent that that you first contacted Kim and brad. Right. Reporter: After saying to this woman "I will not be using your photos ever again." Didn't use her photos ever again. Reporter: Or anyone else's. Uh-huh. Reporter: If you lied to her why should we believe you now? I'm not asking you to believe me because like I said, it's my actions are going to speak louder than my words. Reporter: She insists for her, it was never about gifts or money. I never asked for anything from them ever. Reporter: Does it matter to you that she didn't ask for money is. Yeah, I think that's sicker. I would have welcomed the thought that this was something as simple as a woman look -- scamming you. Then it's like okay at least money's involved. When she was all along really careful to not do that. Then you realize she's just enjoying this. Reporter: It Mae by motherally wrong to fool someone online but not necessarily illegal. She hadn't technically committed a crime because she didn't ask for money. That shows you what a pro she was. Except as it turns out, hope Jackson wasn't such a pro after all. Let's figure out which laws she broke.
This transcript has been automatically generated and may not be 100% accurate.