-- No one can forget how beautiful Mary Horton Vail was.
"Mary was one of those people, when she walked into the room, she made everybody feel good," Will Horton, Mary's younger brother, told ABC News' "20/20" for a story in partnership with The Clarion-Ledger/USA Today Network.
"She was a beauty for sure," Cathy Robbins, Mary's sorority sister, said. "Not only pretty on the outside but pretty on the inside. People really were drawn to her."
Mary was her high school's homecoming queen in Eunice, Louisiana. She went to college at McNeese State University, where she was a member of a school sorority.
Though many men on campus were attracted to Horton, she only had eyes for Felix Vail, a chemical plant worker.
"She just kind of fell in love from the get-go," Cynthia Lunn, Mary's friend and sorority sister, said.
But Mary's friends said they didn't like Felix Vail, and they can't remember why.
"I think Felix was the bad boy," Robbins said. "For some reason, we didn't care for him, I do remember that."
Mary and Vail married in 1961 and started their life together in Lake Charles, Louisiana. After one year of marriage, they had a baby boy named Billy and thought there was another baby on the way.
Mary's brother said his sister and Vail's marriage started out happily. "The family was beginning to start, you know?" Will Horton said.
But her sorority sister said she remembers that Mary had a mysterious premonition about her life.
"I remember in the dorm that Mary had always told us she was going to die young by drowning. I never forgot that," Robbins said.
On Oct. 28, 1962, Mary's fear tragically came true.
That Sunday evening, Vail says he took his wife out fishing in the river, and the two stayed out past dark. In a freak accident, Vail said Mary spotted a stump in the water. He claims that he swerved to miss it and the jolt threw his wife into the river.
Vail said he dove into the water to try to save her but couldn't.
Two days after she disappeared, Mary's body was discovered. The coroner at the time ruled the death an accident, but deputies at the time doubted Vail's story.
Deputies point out that Felix had wasted critical time to go several miles downriver before finding help. There were also two life insurance policies worth half a million dollars in today's money. One of them was taken out and paid in full just months before her death.
Jerry Mitchell, an investigative reporter for the Clarion Ledger of Jackson, Mississippi, whose stories about this case appear in the USA Today network documentary series called "Gone," has been on a quest to find out what really happened to Mary Horton Vail.
In Mitchell's search for answers, he found out that most of the police records have vanished. However, the most important evidence in the case– two gruesome photos of Mary's body – came from a civilian who was on one of the boats that found her body.
The photographs raise several questions. Mary's body was oddly positioned, and oil stains on her clothes don't seem to fit with a drowning, experts later said. A report found with the photographs also said there was a bruise at the back of Mary's head, Mitchell said.
"She has a scarf in her mouth, like four inches into her mouth," Mitchell said. "The theory of the deputies at the time was that, that Felix Vail may have hit his wife with an oar."
Friends and family say Vail seemed to handle Mary's death remarkably well. Her sorority sister Judy Turney, who drove Felix to the funeral, said he "seemed to be very flippant and not in mourning at all."
And even after he collected insurance money, Vail didn't pay the funeral home, according to Mary's brother.
"So he got money, enough to cover the funeral and never put a penny toward the funeral, his own wife's funeral," said Will Horton.
"I think we all suspected Felix from the get-go," Robbins said.
Vail was arrested and held for three days. The prosecutor brought the case to a grand jury, but then dropped it, and Vail moved on with his life.
Fifty years after Mary's death, Mitchell found Wesley Turnage in 2012, who told him that Vail confessed to him that he was a murderer.
"He said, 'Well, that damn ***** wanted another baby … thought it might help save our marriage, but said I didn't want the one I got, and I sure didn't want another one.' …he said, 'I fixed that damn *****. She won't never have another one.' And right then I knew that I was sitting beside a murder," Wesley Turnage is heard saying on a recording of his interview with police on March 2, 2013.
Mitchell found other witnesses who say Vail confided in them. The reporter led prosecutors to Robert Fremont, who was friends with Vail in California in the late 1960s.
"He talked about something about a lake and a boat and all this stuff and he had killed his first wife. I thought it was maybe some kind of B.S. story. They second time he told me, it was very graphic, and it really troubled me," Fremont is heard saying on a recording of his interview with prosecutors. "It sounded like he wacked her on the head and threw her in the water."
But neither Turnage nor Fremont reported their conversations with Vail to police at the time, and Vail went on to marry again.
Vail met his wife, Annette Vail, in 1982 when she was just 15 years old, and he was 44 years old. The two first saw one another in Texas when Vail was driving his motorcycle through her neighborhood.
"I didn't know enough about him for it to raise alarms, and I thought it was casual," Annette's mother Mary Rose said.
While Annette was away at an out-of-town special music school, Rose learned that her daughter and Vail were secretly dating. The couple married in 1983. Since Annette was only 17, she had to have her mother's permission to marry him.
"What I did then by letting her go off with Felix is not something I'm proud of. Yeah, and I trusted her. And I really thought she was in love with him and I didn't know he was a bad guy," Rose said. "I've struggled with it tremendously."
After Annette graduated, the couple took off of a cross-country motorcycle adventure. The trip lasted months, and Annette returned without Vail. She told her mother that she had a painful abortion and wanted a divorce and to move back in with her.
"It was not at all like her to that easily get rid of a baby," Rose said.
Annette isolated herself in a room at her mother's home, calling it "silent therapy" that she needed. Rose brought her food and water, but Annette spoke to no one, including Vail, who repeatedly called on the phone, Rose said.
When Annette told her mother that she was going to emerge from the room soon, Vail heard that and showed up at the home, convincing the young woman to let him back in her life and to push her mom out, Rose said.
Rose said her daughter and Vail all but demanded that she vacate the property. The house and cottage were both bought with life insurance money left to Annette when her father died.
"All of a sudden, Annette puts Felix on the deed with her, and then month after that she actually deed the house completely to Felix," Mitchell said.
Vail then had his wife back, her house and the $98,000 she had left from her life insurance payout. The two then left for another trip through the Midwest. But this time, Annette didn't come back.
"He said they were in St. Louis camping and she decided to go back to Mexico and leave him, so he put her on a Trailways bus and that was his story," Rose said. "I wanted to believe it, and I wanted to believe that I would hear from her."
For more than 20 years, Rose went to prosecutors, police, private investigators and even psychics to try to turn her suspicions into a case against Vail.
"I never let go of hope that maybe, maybe, maybe, he would -- people -- somebody would believe what I knew to be true," Rose said.
It wasn't until 2010 when Rose met Clarion Ledger reporter Jerry Mitchell that she found someone to help her.
"The very first thing she asked me was, 'Would you be interested in writing about a serial killer living in Mississippi, and I was kind of like, 'Yeah,'" Mitchell said.
"I was going to Mississippi. I said, 'I'm gonna confront Felix, would you like to meet me there?'" Rose said.
At Vail's trailer in Mississippi, Rose, then 64, climbed in through a broken window determined to look for evidence. Inside, she said she found a number of machetes.
Later, Rose told Mitchell that there was another woman that Vail had been with named Sharon Hensley.
In the late 1960s, Vail met Hensley in San Francisco at a pot party. Neither had jobs, and the two brought Vail's 8-year-old son Bill with them as they hitchhiked the coast, stealing from orchards to eat and dropping acid.
At the time, Bill was not in school, ran barefoot, and his only possessions were shorts and a sleeping bag, Mitchell said.
"So, one day basically the son marches to the police department and tells the police, 'My dad keeps giving me drugs and I don't want drugs," Mitchell said.
Billy also told police that his father confessed to Sharon that he killed Bill's mom Mary Horton Vail. Two sheriff's deputies from Calcasieu Parish, Louisiana, flew to California, but Vail didn't speak and no murder charges were filed.
"He knew what he had heard, and he never wavered on that, never," Janet Vail, Bill's widow, said.
Janet Vail said her husband purposely left his story on a church podcast before he died of cancer in 2009, because he "wanted the truth to come out here for the victims."
"He didn't even know I was in the house. Overheard him just sobbing, which caught my attention, and he told her that he murdered my mother. He said, 'No, you don't understand. I really did kill her,'" Bill is heard saying on the podcast. "That's when I found out the truth of my mother's death."
Up in North Dakota, Brian Hensley, Sharon Hensley's brother, saw the story of a young Bill going to the police department in a newspaper at a supermarket. The last time he saw his sister, she had wasted away from bad nutrition and drugs. Brian Hensley said Vail was in total control of his sister's life.
"At that point, I believe she was with him out of fear. She didn't know how to get out of the situation," Brian Hensley said.
Sharon Hensley told her parents that they were hitting the road, possibly to South America. She later sent a photo captioned, "making travel plans," but the family said they saw no excitement in her eyes, only sadness. They got one last phone call from her.
"And that-- when my mom got off the phone, she told me dad, 'Sharon's in deep trouble. She's crying out for help,'" Brian Hensley said.
But they didn't know where she was and didn't know how to help, and they never heard from Sharon Hensley again.
"And so, about a year later, Felix writes a letter to the Hensley family basically saying, 'Oh, I haven't seen Sharon, you know. Last I saw her was about a year ago, we were down in Key West,'" Mitchell said.
There was no investigation, but when Vail returned home alone, Bill said his dad told him another chilling story about Sharon Hensley.
"He said she would never bother anyone ever again. I knew what that meant. I knew he had murdered her," Bill said on the podcast.
Gina Frenzel, a private investigator who goes by the nickname "Batgirl," offered to help Jerry Mitchell with his story, after reading Mitchell's book, "Gone."
When she found out he lived just an hour and a half away, she went to see him. Vail was living in a shack with no running water. The year before he lived there, there had been a suspicious fire next door.
Frenzel told Vail she was there to investigate the fire, and he allowed her to walk around. Frenzel took photos around the property, including a rare image of Vail in his 70s.
"There was this big plastic Rubbermaid tote and of top of it's a little toolbox, and there's a hacksaw and a hammer right on top of it and that's all that was going through my mind was, 'Holy crap,'" Frenzel recalled.
Frenzel returned a week later, telling Vail she needed to take more photographs. While with Vail, she had her audio recorder rolling and hidden in her bra.
They spent the next six hours sipping wine and talking about his philosophy of life. Frenzel said she was bored, but feigned interest in order to gather clues, including when he seemed to admit he knew a lot about murder.
"He doesn't know how much I know about killing myself, you know, about killing people," Vail is heard saying on Frenzel's recording.
In another alarming moment, Frenzel said he thought Vail was speaking about the still missing Annette.
"I said, 'Do you ever see her anymore? And man, his body language completely changed. His color went. He stepped towards me and his eyes turned black and it was all instant. But man, I hit a nerve," Frenzel recalled.
As Frenzel got to know him, Vail, at one point, thought Frenzel was his girlfriend. Frenzel said she visited Felix four times and that there was no physical contact except for their goodbyes when they hugged.
Later, Vail asked Frenzel to do some chores from him when he wasn't there. She used the opportunity to snoop around his house and found a collection of women's earrings.
"He's probably got 13, 14 pairs of earrings here, and kind of makes you wonder whose were they and why does he keep 'em?" Frenzel said.
She also discovered a bin filled with more than 20 journals. Frenzel meticulously pored over the 2,000 photographs she took of the journals.
There were no clues, except for what he wrote about how he would handle a situation. He wrote, "I was altered by it in a positive enough way to enable me to handle, without murder, the upcoming debacle." Frenzel says this line could be interpreted as an admission that he may have murdered before.
He also wrote about Beth Field, an ex-girlfriend from the late 1980s.
Field told us she and Vail got together after Annette went missing, and she said she was immediately attracted to him. But one day he became violent.
"He just turned around and started hitting me. He actually broke my ear drum. I had a black eye. I had bruises on my arms. He hurt me," Field said.
Field says after a second beating she ended the relationship realizing that Vail was a sick man.
On May 17, 2013, Vail was arrested by police, accused of killing his wife Mary Horton Vail.
Today, Vail is 76 years old. He is awaiting trial in Calcasieu Parish Jail on charges of murder. And the disappearances of his companion Sharon Hensley and his wife Annette loom large.
"The thing that all three women have in common is the fact they were all last with Felix Vail," Mitchell said.
District attorney John DeRosier says without Mitchell, the case may never have reached where it is today.
"Jerry Mitchell came in with a family member of the deceased and explained the case to me and concluded that it was certainly worth investigating," DeRosier said. "Without him, we may not be here today."
DeRosier says the fact that trial court Calcasieu Parish 14th District Court will allow the disappearances of these two other women as evidence in this trial is highly unusual.
"It is because of what we considered to be the doctrine of chances. Something extraordinary happens on time, you know, it can happen to anybody. The more it happens, the less likelihood it is that it's either an accident or just by chance," DeRosier said.
Vail pleaded not guilty, and his attorney Andrew Casanave says he didn't commit these crimes or any other and blames his entire prosecution on an overly zealous Mitchell.
"People have disappeared and shown up 50 years later more than a few times. I would not be surprised if one of these women we suddenly found out was in a nursing home in Cleveland. The truth is that state doesn't have what it needs to make a normal murder case," Casanave said.
"All I can say is that it just brought me joy to know that after all these years justice can still be done," Annette's mother Mary Rose said.
"When justice comes, it brings joy. This'll be 50-something years later and they're experiencing justice for the first time," Mitchell said. "That's incredible."