Almost immediately, Dr. Hisam Goueli could tell that the patient who came to his psychiatric hospital on Long Island this summer was unusual.

The patient, a 42-year-old physical therapist and mother of four young children, had never had psychiatric symptoms or any family history of mental illness. Yet there she was, sitting at a table in a beige-walled room at South Oaks Hospital in Amityville, N.Y., sobbing and saying that she kept seeing her children, ages 2 to 10, being gruesomely murdered and that she herself had crafted plans to kill them.

“It was like she was experiencing a movie, like ‘Kill Bill,’” Dr. Goueli, a psychiatrist, said.

The patient described one of her children being run over by a truck and another decapitated. “It’s a horrifying thing that here’s this well-accomplished woman and she’s like ‘I love my kids, and I don’t know why I feel this way that I want to decapitate them,’” he said.

The only notable thing about her medical history was that the woman, who declined to be interviewed but allowed Dr. Goueli to describe her case, had become infected with the coronavirus in the spring. She had experienced only mild physical symptoms from the virus, but, months later, she heard a voice that first told her to kill herself and then told her to kill her children.