The ads don't include the inmates' criminal history, but most states have online databases that list prisoners' offenses and release dates. InmatesPlus.com hosts links to individual states' sites, where visitors can search for information on specific inmates.
McDonald was aware of Harris' crime before he proposed, but, like many partners of inmates, he is convinced of his wife's innocence.
"She killed no one, but was there when someone else did. The conviction was in a small rural Southern community. Justice is different there," he said. Harris and her two co-defendants were represented by court-appointed attorneys. Each was sentenced to life in prison without parole.
Psychologist Elaine Aron, author of "The Highly Sensitive Person in Love," agrees with her husband's assertion that some people may actually seek out relationships with prisoners because it fits their personality type. One such personality type may be the "highly sensitive person," about 15 percent of the population, according to Aron.
An HSP is someone who is particularly empathic and often struggles with overstimulation in daily life and intimate attachments. "Their issues could dovetail quite neatly with an inmate. … They would feel particularly compassionate or sympathetic to an inmate, and at the same time feel comfortable with a relationship that comes with predictability and defined boundaries," she said.
Psychologists and researchers say individuals with a history of abuse or low self-esteem may be more likely to fall in love with a person who has committed a violent crime. Should they enter a correspondence with an inmate, they could be particularly vulnerable. "Many people in jail are sociopaths and they're very good at manipulating people," said Aron.
Sheila Isenberg said the women she interviewed for her book "Women Who Love Men Who Kill" had all experienced some sort of abuse in their past, either in their family or with a past spouse or boyfriend. "Some of these women may actually feel safer in these relationships," she said. "When their partner is incarcerated, he can't hit her or be abusive."
Grant said that may explain some of the relationships with the inmates at Joseph Harp as well. "He's not going to beat you. He's not going to be sexually abusive. He's going to be nurturing to you, and you don't need to worry a whole lot about him running around on you," Grant said.
Men who fall in love with women inmates may be casting themselves in the position of a rescuer or defender, says Isenberg.
This may not be the foundation of McDonald's love for Harris, but he is committed to working for her ultimate release. "We hope for relief. We cannot plan on it. But she was wrongly incarcerated and I took it as my citizen duty to right the injustice. Thus, there is a political crusade here," he said.
McDonald says, and prison officials confirm, that he visits Harris weekly, but he says he feels the sting of their separation during the week. "Clearly I feed off her every weekend in visitation. The relationship is very intense, very open. The negative side is spending the weekdays alone. I generally write her a few lines every day or a few pages depending on what is on my mind, but I still have to cook dinner for one, sleep alone," he said.
And while psychologists and researchers attach a host of Freudian theories to women's romantic interest in violent criminals, McDonald says Freud's protégé Carl Jung has a better take on the male-female dynamic between himself and Harris. "I must verify Carl Jung's identification of the anima in males, the animus in females. … Very clearly my wife represents the projection of my feminine side just as I represent the projection of the masculine side in her. As we both become aware of this, the relationship intensifies and there is a sharing of the inner self, those secrets no one knows. … In simple language, neither of us will ever be lonely again."