DES MOINES, Iowa (AP) — A former state lawmaker accused of raping his wife in a nursing home is forcing an Iowa court to confront a little-discussed question of aging: When is a person suffering from dementia unable to consent to sex?

The case centers on Henry and Donna Lou Rayhons, both 78, who got married seven years ago in a union that seemed to offer a second chance at love for the two, who had both been widowed. But their domestic routine of church activities and political functions unraveled as Donna’s health began to fail.

Last year, Donna Lou Rayhons was moved into a nursing home because she was suffering from dementia and Alzheimer’s disease.

A family conflict developed over how to care for her, culminating in a meeting in which the nursing home staff told her husband that his wife was no longer mentally capable of legally consenting to have sex.

State prosecutors say Henry Rayhons — then a long-serving Republican state representative — ignored that message. On Wednesday, he will stand trial for sexually assaulting his wife, who died in August. The charges were filed days after she died.

Many older couples experience the hardships of illness, mental decline and living apart, but what happened with the Rayhons has little precedent. Experts could not recall another rape case that happened because a previously consenting spouse could no longer legally acquiesce.

“This is the first one I’ve seen,” said Mark Kosieradzki, a Minneapolis-based attorney who has tried numerous cases of sexual abuse in nursing homes. “It’s a case that’s going to be focusing on the rights of the vulnerable. Just because you’re married, it doesn’t mean you need to check your consent rights at the door.”

Through an attorney, Donna Lou Rayhons’ daughters from a previous marriage declined to discuss the case. The state attorney general’s office also declined. And Henry Rayhons, who has said that he is innocent, refused an interview through a son.

When the charges were first filed, Henry Rayhons’ family released a statement.

“Donna’s location did not change Dad’s love for Donna nor her love for him. It did not change their marriage relationship. And so he continued to have contact with his spouse in the nursing home; who among us would not,” read the statement, which went on to call the charges “illogical and unnatural.”

The crux of the case is the question of Donna Lou Rayhons’ ability to consent. Iowa law defines an act as sexual abuse in the third degree if the two parties are not living together as husband and wife and if one person “is suffering from a mental defect or incapacity which precludes giving consent.”

Elizabeth Edgerly, a clinical psychologist who serves as chief program officer for the nonprofit Alzheimer’s Association, said determining capacity is challenging.

“Is the person capable of saying ‘no’ if they don’t want to do something? That’s one of the biggest pieces,” said Edgerly, who frequently lectures on sexuality and Alzheimer’s.

But Edgerly also noted that patients can vary day to day and said that physical closeness can be reassuring to many, noting: “For most people with dementia, even long into the disease, they take comfort in being with people who love them.”

Rayhons is charged with third-degree sexual abuse and could serve up to 10 years in prison if convicted. Shortly before the charges were filed, he withdrew from a race to serve a 10th term in the Iowa House.

The Iowa attorney general’s office sought to move the trial out of Hancock County, where Rayhons lives, arguing that they would not be able to find an impartial jury after the extensive news coverage. But a judge denied the request.

Court documents provide a window into the bitter case, which has left a family divided.

Donna Lou Rayhons was moved to a nursing home in Garner in March 2014. According to her husband’s family, the move was the decision of her daughters. In mid-May, Henry Rayhons was informed of his wife’s inability to consent.

According to court documents, he entered his wife’s room about a week later and pulled the curtains around her bed. A roommate heard noises that suggested sexual activity. As Rayhons left, he dropped undergarments in a laundry basket.

Not long after that, one of Donna Rayhons’ adult daughters went to court and won temporary guardianship.

A state crime lab found semen stains on Donna Lou Rayhons’ quilt and a sheet that matched Henry Rayhons’ genetic profile. The charging document says he confessed to sexual activity that night, but in an interview last year on the “Dr. Drew On Call” show on the HLN network, his son Dale Rayhons said the police interview was taken out of context.

Dale Rayhons said in a recent statement to The Associated Press that he supports his father, adding that: “to have found love and companionship this late in their lives was an extraordinary and special thing for both Dad and Donna.”