(CBS) On a hot August night, 56-year-old Sandra Franklin calls police to report a violent confrontation.
911 Operator: Bainbridge 911, what is your emergency.
Sandra Franklin: Yes, my husband just attacked me and I stabbed him.
911 Operator: OK, what's your address?
Sandra Franklin: 9495 Stafford...
911 Operator: And you stabbed him with what?
Sandra Franklin: With a knife, a kitchen knife....
As paramedics and police in Bainbridge, Ohio, rush to Sandra's horse farm, oddly, a second call comes in from the same address - this time from the victim himself, 73-year-old Peter Franklin.
911 Operator: What's the problem there
Peter Franklin: Stab wound...
911 Operator: You were stabbed with a knife? Who stabbed you?
Peter Franklin: My wife...
911 Operator: Did she do it intentionally?
Peter Franklin: Yes
Listen to their 911 calls
He's stumbled into the backyard, bleeding heavily from a single stab wound to the chest.
Within hours, Peter Franklin was dead, and his wife, Sandra, was charged with his murder.
"I am absolutely not a murderer," Sandra tells "48 Hours Mystery" correspondent Peter Van Sant. "There isn't a day that goes by that I don't cry... I still love my husband..."
But what could have brought a loving relationship to this?
Sandra and Peter's love affair had started nine years earlier. "He was just a - a fantastic figure of a man to me," she says.
After several failed relationships, they both felt they'd finallymet the love of their lives.
"He was a doctor," Sandra says. "And I loved that about him, too, that he was out there helping people."
In fact, since his early 20s, Peter Franklin's whole life had been about helping others.
"He was a person who cared deeply for other people. He wanted to go and learn different things about different countries," says Peter's first wife, Liz Franklin.
Peter and Liz met in her home country, South Africa, while he was in the Peace Corps in the early 1960s.
"And he also wanted to go to Vietnam to help somehow there," she says.
After the Peace Corps, Peter did go to Vietnam, volunteering to help wounded children trapped in the war zone. The experience inspired him to become a doctor.
Asked if Peter was a good man, Liz tells Van Sant, "I think he was a very good man. He could drive you nuts, but he was a very good man ... Peter Franklin was brilliant, but he could be infuriating with his detachment."
Peter and Liz settled in a small town just outside of Cleveland, Ohio, where Peter started a family medical practice.
In 1965, the couple had a son, Bram; everyone called him Brami.
Tragically, while on a camping trip with his father, Brami was killed in a freak accident while playing near an abandoned gas tank. He was just 10 years old.
Liz says their son's death had "a hugh impact" on Peter. "He was very, very sad and...really missed him very much."
While grieving, Liz became more aware of the odd quirks in Peter's personality.
"He didn't form attachments easily," she says. "He was withdrawn and unable to express his words."
After Brami's death, Peter and Liz drifted apart and their 17-year marriage ended in divorce.
Three years later, Peter met Bobbi Arters, a single mom of two boys.
"When I met him, he was a kind and very generous person... My sons were 12 and 13. They looked up to him," Bobbi says. "And I think if anything I could thank him for is... my one son is a doctor now and the other son's an engineer ... And they quite - recall all the good things he did for them," she continues, in tears. "He was such a good person."
During their two years together, Bobbi introduced Peter to the world of horses.
"He wanted to learn to shoe his own horse... he wanted to learn to jump... and he would just dive into it and learn it," she says.
But like Liz, Bobbi noticed there was a strange underside to Peter's personality.
Asked if Peter could be exasperating at times, Bobbi tells Van Sant, "he could be because he lacked the emotion and the awareness that I think a woman or most people would want."
It led to their breakup, and Peter remained one of the most eligible bachelors in the county for years... until he met Sandra.
"This was an amazing thing, to fall so deeply in love with somebody so quickly... We would go hunting. And the rest of the group couldn't find us. They would get angry with us because we'd be dropping off and dropping off, and get lost in the woods together," she recalls with laughter. "I mean, it was just - so spectacular. There's nothing quite like being in love."
But the two of them had come from different worlds. While Peter had grown up wealthy in New York City, Sandra came from a poor family in rural Ohio.
"We lived in trailer parks quite a bit....and my mother was the breadwinner," Sandra says. "I was horse crazy from the time I was 3..."
Through horses, she made a career of teaching riding to children. "And I just loved the interaction... that I had with the kids, and it was really just a wonderful, wonderful life," she says.
It was a wonderful life she hoped she'd continue with Peter.
Three months after their first date, Sandra became Mrs. Franklin. "And this was the start of something that was going to be just the best thing in my life," she says.
But, she says, the romance quickly faded. "I think he has something wrong with him. He would hit me. He would... pick me up and throw me."
"It was kill or be killed," Van Sant remarks.