An unbreakable bond between a mother and a daughter. Nothing could drive a wedge between Angie Yarnell and her mother Marianne. And that tight relationship would help solve one mystery and leave another still to be solved.

Nobody may have ever uncovered the terrible truth about Angie Yarnell if it hadn't been for her courageous and tenacious mom Marianne Asher-Chapman, who was already fighting throat cancer when she suddenly found herself waging yet another battle to learn what really happened to her daughter.

"I tried to find help. I could not find a soul that could help me. Nobody seemed to know what to do," said Marianne Asher-Chapman, Angie Yarnell's mother.

But Marianne believes it was her determination to get to the bottom of her daughter's case that actually helped her beat the throat cancer, just so she could speak for her.

"I had to find my voice and I had to fight," said Marianne. "I had to fight real hard to get the things done that I've gotten done."

Angie was Marianne Asher-Chapman's only daughter. Angie was born and raised a simple country girl in the little town of Holts Summit, Missouri.

"Angie has always been just a really unique person," Marianne tells Crime Watch Daily. "Funny little child. She was an artist. She loved art and poetry."

And her pets, which had made her dream of a career working with animals.

"She loved her dogs. Her dogs were her children, and she loved dogs and cats and animals," said Marianne.

Angie had also hoped to have children one day with her husband of three years, Michael Yarnell.

"She seemed real happy with him. At first, anyway," said Marianne.

But Marianne says the couple quickly began having problems in their marriage.

"Early on, she told me that he was emotionally and verbally abusive, but then they seemed to work it out," said Marianne.

Until Michael accused Angie of being unfaithful.

Did Angie ever have an affair?

"No," said Marianne. "He said that she had been having an affair. But it was he in fact that was having the affair with a woman also named Angie."

And Marianne says the marriage finally collapsed.

"But she never expressed anything other than toward the end he said he was leaving her," said Marianne.

But then, shocking news: when Michael turns up at Marianne's home one day to tell her that Angie has just left him:

"He said 'Well, she's gone now,'" said Marianne. "I said 'What do you mean she's gone?' He said 'I think she must have ran away with another man,' and I said 'Well, who'd she run away with?' He said 'I don't know. I came home and she was gone.'"

Marianne is dumbfounded.

"Surely she would have let me know something about some guy, right? But she didn't," said Marianne.

Especially as Angie, 28, had been helping care for her mother as she battled cancer.

"She certainly wouldn't have left me sick like that," said Marianne.

And when she still hasn't heard from Angie by the following day, Marianne files a missing-person report.

"They didn't want to accept it at first. They said 'She probably did run away with another man,'" said Marianne.

Marianne hopes police are right.

"I'm trying to fool myself because I don't want to admit that she's dead," said Marianne.

In the weeks after Angie went missing, her mom received a very odd piece of mail that played a huge role in the case.

"Ten days later that I receive a postcard, and it was postmarked from Harrison, Arkansas," said Marianne.

It reads: "Mom, we are going to Texas tomorrow to visit Gary's family. Will write soon as we are settled. Love, Angie."

"And I said, 'Dang, she really did go with some guy, and his name is Gary,'" said Marianne.

Marianne was even looking forward to meeting Angie's new man at Thanksgiving in just a few weeks' time.

"She always knew how I was about holidays," said Marianne. "Everybody needs to come here because it's a holiday, and I was certain she would be here and bring Gary. She would not miss Thanksgiving."

But she'd miss this one. As more weeks go by with no word from Angie, her increasingly despairing mother starts examining that postcard a little more closely.

"I could tell it looked sort of like her writing, but not her normal writing," said Marianne.

Now Marianne finally accepts the truth she'd tried so hard to not let herself believe.

What leaped out to you that finally made you say, "Wow, this actually is a forgery"?

"I could just tell," said Marianne. "Even in the beginning, I said 'It's not her normal writing.' There were a lot of dots where it was like written really slowly, and some of the letters I've never seen her write like that."

Angie Yarnell had never mentioned anyone named Gary to her mother, and it was unlike her daughter to just up and leave their little hometown of Holts Summit, Missouri, without at least saying goodbye.

"Instantly, I knew something was very wrong," said Marianne Asher-Chapman.

When months go by with no more word from Angie, Marianne comes to believe the postcard was a forgery and turns detective trying to find her.

"I hung thousands of fliers. I drove to different states to hang fliers, I put them on windshields in parking lots. I got billboards. I did everything I could with local TV," said Marianne.

All that while battling throat cancer.

"I was physically really unhealthy. I mean I lived on the verge of tears, and it was just really hard, just really hard to not know where your person is. Especially your child," said Marianne.

But for several years, Marianne made no headway in her search for Angie -- until her heartbreaking plight comes to the attention of a local newspaper reporter.

"It was sad to see that Marianne had done this enormous investigation on her own, so that's what really reeled it in for me," said Jefferson City News-Tribune Reporter Ra'Vae Edwards.

Edwards wrote a story about Angie's disappearance for the News-Tribune that attracted broad media attention.

Four years after her daughter went missing, Michael Yarnell was named a person of interest in the case. But before police could talk to him, he disappeared.

"I was told by his stepmother that he left town with his clothes tumbling in the dryer," said Marianne.

Never to return to the home he once shared with Angie.

Marianne, who had always suspected Angie's husband may have had something to do with her disappearance, is convinced the media spotlight on the case had driven him into hiding. Marianne and her new ally Ra'Vae Edwards figure the best chance of locating Mike Yarnell is to have police list him as a missing person. And Edwards had also arranged for a professional handwriting expert to examine that strange postcard Marianne had received after Angie first disappeared.

Peggy Walla has worked on numerous criminal cases for police. She compared the postcard to other samples of Angie's handwriting, immediately noticing numerous differences.

"The first thing that jumped out at me was the shape of the ends of the esses. It was also lacking a hook at the bottom of the first stem of the capital letter 'H.' The 'n' formation was different. The 'g,' the lower-case 'g' formation was different," Walla tells Crime Watch Daily.

She quickly come to an unquestionable conclusion:

"So when I got the postcard and the samples, I said she didn't write it," said Walla.

But that's not all Peggy Walla discovered. After also comparing the writing on the postcard to that of Michael Yarnell's on a handwritten statement he'd given to police at the time of Angie's disappearance:

"I said 'This is the hand that wrote the postcard,'" said Walla.

"I wasn't at all surprised, not in the least bit surprised at that point," said Marianne.

"I knew that was going to be our key to get him charged with something," said Edwards.

"And from there it just snowballed," said Walla.

That missing-person report that Marianne and Ra'Vae Edwards had filed On Michael Yarnell finally paid off when he showed up in Biloxi, Mississippi.

"Mike Yarnell had applied for a civilian job on an Air Force base there, and they did a background check and saw that he was listed as a missing person," said Marianne.

He was detained and the Morgan County Sheriff's Office in Missouri was alerted. They sent two detectives down to talk to Yarnell.

Confronted with the results of that handwriting analysis by Peggy Walla, Mike Yarnell came clean about that postcard Marianne received a week after her daughter's disappearance.

"Mike admitted that he sent that postcard with the thought of throwing law investigation off and giving Marianne a little bite of peace," said Edwards.

After being extradited back to Missouri on felony charges of forgery and tampering with evidence, Mike Yarnell ultimately confessed to killing his wife Angie during an argument at their home.

"He said that they'd gotten into a fight and it spilled out onto the deck," said Marianne.

"And that she lunged toward him and that he put his arms up in an 'X' motion in front of his face and shoved her," said Edwards.

"And he said she fell off the deck and hit her head on a rock and died instantly," said Marianne. "And he said he sat with her for a while, then he wrapped her up in a tarp and he put her in the car."

And drove to a nearby lake, put her body in a canoe and rowed to a deserted little island.

"But when he was right at the shore of the island, the boat fell over and she sank into the mud and he couldn't get her out, so he just left her there and went home," said Marianne.

As part of a plea deal Mike Yarnell made with prosecutors, he agreed to lead police to Angie's body.

"They followed him to the island where he claims he lost her body. Nothing was ever found," said Edwards.

Which makes Marianne furious.

"Nonetheless they decided to give him the plea bargain anyway," said Marianne.

Prosecutors dropped murder and other charges against Mike Yarnell in return for him pleading guilty to a much lesser charge of first-degree involuntary manslaughter.

"He was handed seven years and he spent exactly four years in a minimum-security prison," said Marianne.

He was released early for good behavior.

"It was sad to watch this man get by with killing his wife mainly because he hid her body so well that they had no proof," said Ra'Vae Edwards.

But prosecutors had told Marianne that even with his confession they doubted they could win a murder conviction against Yarnell.

"Even though he said he killed her, they had no evidence, and the evidence is literally her body," said Marianne.

Now, 15 long years since Angie was killed, her still-grieving mother continues to search for her, saying she suspects Mike Yarnell lied about how she died, and she believes her daughter's body is buried somewhere on the property where the couple used to live.

"I've searched that property like you can't believe, for so many years," said Marianne. "I mean, I take a shovel and I go down there, I dig holes, I crawl under houses. I've been in the bottom of sink holes. I've been in caves. I've sifted through big burn piles. I've looked in barrels. I do this. I look for Angie."

And Marianne, who ties a ribbon around a tree at her home every year Angie remains missing, swears she won't stop looking for her daughter's body until she finds it.

"I just need to bring her home. I won't quit. I won't quit looking. I will look for her. As long as I'm physically able, I go look for her," said Marianne Asher-Chapman.

Sadly, even if Angie's body is found, double jeopardy laws would prevent Michael Yarnell from being tried again.

Crime Watch Daily did ask the Morgan County Prosecutor and the Sheriff's Department for on-camera interviews. They both declined.

The prosecuting attorney sent us this written statement: "You're welcome to reach out to them "-- them being the sheriff's department-- "but my advice to them is that we cannot jeopardize other possible prosecutions by making public comment. -- Dustin Dunklee, Morgan County Prosecuting Attorney"