The community of Belleville, Illinois rallied for Alissa Jackson, a mother of five in the middle of fighting cancer. But she was hiding a very dark secret.

Alissa Jackson told friends and family she had the "Big C": Stage 4 ovarian cancer that was spreading to her organs and brain. She was going to die, leaving her five children without a mother, and her husband a widower.

"I first met Alissa Jackson at school. I passed her in the hallway. She was visibly sick," said Jenn Huelsmann. "She had a bald head, she had IV tubing hanging from her chest, she was walking with a cane and she had all of her children with her."

Huelsmann will never forget the moment she struck up a friendship with Jackson at a school volleyball game.

"I decided I was going to introduce myself. I was really nervous. She immediately started telling me her story," said Huelsmann. "She said she had Stage 4 ovarian cancer, she wasn't really doing well after this round of chemo. Our friendship started from there."

Huelsmann whipped up homemade meals and brought them to Alissa's family. Soon word got out about the young mother's dire situation, and the support rolled in.

"There was a prom held for her, someone donated a minivan to the family, someone sent Alissa and her husband on a romantic getaway vacation," said Huelsmann.

All in all, Huelsmann estimates, Alissa raked in well over $50,000.

Alissa Jackson, a 31-year-old nurse with five young children, faced with terminal cancer, touched the hearts of people all over the country.

"People would send things through Amazon. Gifts and treats, household supplies were collected," said Huelsmann. "The list is just endless of ways people found to reach out and support Alissa and her family."

As a barrage of gifts and cash poured in, Alissa started a website called "Alissa's Army," where she would keep people up to date on her condition.

"She used Alissa's Army page to blog daily about her medical condition," Huelsmann said. "She would post updates about her treatments, how she was feeling."

In one post Alissa wrote: "I've been extremely sick this past week. I can't keep anything down. I'm coughing/throwing up blood clots the size of cutie oranges at times."

Here she asks for advice on how to talk to her kids about her impending death: "I've explained that there's bad things growing inside of me making me sick. Now my 4-year-old keeps asking me if I am going to die."

"She would also link her GoFundMe page to ask for donations and let people know that she needed food, clothes for her children, things like that," said Huelsmann.

After about nearly two years of this, one night Huelsmann got an urgent text from Alissa saying she was being rushed to the hospital coughing up blood and was ready to die alone.

"I rushed to the emergency room. I got there and they said no Alissa Jackson," said Huelsmann. "I was texting , so she sent me a picture she sent me a selfie of herself in the hospital gown. So I showed the hospital. And a man from the hospital took me to a cubicle, sat me down and he put her name in the computer and said she is not here at this hospital. He said we checked with other hospitals and she is nowhere. And it was at that moment I realized she's lying."

The pieces of the puzzle started falling into place and Huelsmann realized she'd been duped.

"So that night at the E.R., that's the night that Alissa Jackson died. My friend died that night because everything changed," said Huelsmann. "This woman who I looked up to had looked at her children in the face and told them she was dying of Stage 4 ovarian cancer, and it was all a lie."

Huelsmann knew that if she confronted Alissa about her scam, her now former friend would continue to spin a web of lies.

"I had to come up with some other way to get to the bottom of the truth and stop her in her tracks," said Huelsmann. "That's when I decided I needed to get the help of a private investigator."

Jenn and some other friends turned to Detective Durwood Hurst who ran surveillance and caught Alissa dead in her tracks.

"It was a fraud," said Hurst. "She would tell Jenn that she had a scheduled appointment with her doctor, and we would be observing her at her home of at the Target store."

Her friends are about to learn her illness wouldn't last forever.

"Absolutely floored. Just completely disgusted that somebody can do something like this," said Kathy Carron, who was a victim of Alissa's scam. Friends who showered Alissa's family with cash and gifts worth nearly $50,000 are livid that they were scammed.

"We knew for a fact Jenn's suspicions were correct," said Durwood Hurst. "The lady did not have cancer."

Detective Hurst ran surveillance on the con artist for two months.

Based on his evidence, police made the arrest. Alissa appeared in court, shackled and looking painfully thin -- but not from the fake cancer. Shielding her face from the angry people she duped.

"Her kids were told that their mother was dying of cancer, they were told daily, she would lay on the couch," said Huelsmann. "She was too sick to attend some of their sporting events, she was too sick to attend her oldest's graduation."

Alissa Jackson pleaded guilty to two counts of felony theft. The defense claimed that Alissa was sexually abused as a child and she's a former addict who used meth and heroin. Her attorney says she was lonely and faked cancer not for money, but to have close friends who cared for her.

But forensic psychologist Dr. Julie Armstrong -- who did not treat Alissa -- says her actions could have been more sinister.

"Well, Alissa had a lot of problems. We've learned that she was a heroin addict," said Armstrong. "But because Alissa was a nurse, she knew cancer could mimic the effects of the addiction and so I suspect this is why she pulled on the diagnosis of cancer to explain why she didn't look good and feel good."

And what about Alissa's husband Brandon? He was never implicated in the scam.

"She'll never be sorry, ever. She'll never be sorry," said Amanda Tambor, a victim of the scam. "She's a pathological liar. She's lied her whole life. She lied in high school. She's lying. She's going to continue to lie till the day she dies."

Two years have passed. Alissa appeared at her sentencing with longer hair. She's put on weight and looks much healthier than before.

After years of playing people's emotions and prying cash from their bank accounts, Alissa Jackson is sentenced to three years in prison. And that's not all: The cancer con artist may have to pay back some of the money she swindled from so many of her supporters.

"That matter is not concluded yet," said St. Clair County State's Attorney Brendan Kelly. "It's a fairly complicated matter given the number of the people that were involved and the potential calculations that have to be done in order to determine what an appropriate amount of restitution is."