Wayne Flynt, the Alabama historian and a friend of Ms. Lee, said the author is mentally fit, engaged and can recite long passages of literature. When he visited her a few weeks ago after hearing reports that she was depressed, they spoke about his grandson and she laughed at the stories he told. He said he believed Ms. Lee was capable of assenting to the publication of “Watchman.”

But he also said she occasionally has problems with her short-term memory. When he asked her about her new novel, he said she seemed to be “in her own world” at first, and asked, “What novel?” Reminding her of “Watchman,” he told her “You must be so proud,” and she responded with “I’m not so sure anymore,” Mr. Flynt recalled.

The only statements from Ms. Lee about the new publication — affirming her enthusiasm — have come through her lawyer, Tonja B. Carter, who handles her day-to-day affairs. Ms. Carter came across the manuscript in August and negotiated the book deal with HarperCollins. Over the course of a week, Ms. Carter did not return a phone call and text messages seeking comment. A lawyer for Ms. Carter, Bobby Segall, declined to comment. In a previous interview with The New York Times, she described Ms. Lee’s excitement that “Go Set a Watchman” would be published, and stressed she would never go against the author’s wishes.

One person who said that he had filed an anonymous complaint with the state is a doctor who has known Ms. Lee for years. The doctor said in an interview that he had called Alabama’s adult protective services hotline and asked the state to investigate whether Ms. Lee was too infirm to have fully consented to the publication of “Watchman.”

The doctor, who has not treated Ms. Lee and asked to remain anonymous because of the divisive nature of the issue, said he had been alarmed by reports of her frailty and by an account from someone he trusted who visited Ms. Lee last fall after the death of her sister, and said she was largely uncommunicative, lying in a fetal position in bed in the middle of the afternoon.

The investigation is being led by the state’s Human Resources Department with the help of the Alabama Securities Commission, which among other things, works to prevent financial fraud against the elderly. Barry Spear, a spokesman for the Human Resources Department, said he could not comment on any investigation, noting that such inquiries are confidential. But he said investigations into elder abuse are done at the discretion of the department, based on an initial assessment of a complaint, and they can involve law enforcement if there is evidence of financial exploitation.

Caseworkers generally talk to people who may be victims to evaluate their physical, mental and emotional state, and they interview doctors, family members, caretakers and friends, Mr. Spear said.