A critically ill 84-year-old woman was fatally stabbed with a butcher knife yesterday in her bed at the Washington Hospital Center in what police officials said was a possible mercy killing.

A nurse found the woman, Selena Toye of 3404 13th St. NW, in the intensive care unit with a knife in her chest about 4:40 a.m., shortly after she was visited by a man who identified himself as a family member, police and hospital officials said.

Toye was rushed to surgery but died about 90 minutes later, they said.

Police have not made any arrests in the case. A D.C. homicide detective said the incident "is a possible mercy killing, but a pretty cold one . . . . "

Hospital spokeswoman Stephanie McNeill said Toye had been a patient at the hospital since early July, when she was admitted for treatment of heart disease. She was moved to the intensive care unit Tuesday after she suffered a heart attack and lapsed into a coma, McNeill said.

According to police and a nurse who did not want to be identified, Toye's family was bitterly divided over whether to remove her from machines that were keeping her alive .

McNeill said that Toye's doctor had discussed with family members the possibility of removing her from life support systems. She said that without the machines, Toye would not have lived.

According to one of Toye's granddaughters, Darrena Shelton, 25, who lived with Toye at 3404 13th St. NW, some family members, including herself, were in favor of removing her grandmother from life-support machines. She said her mother was against it.

Her mother would not comment yesterday.

"I'm not saying we wanted her dead," Darrena Shelton said. "We know how she was . . . and we just know she didn't want to be laying there . . . . I just don't like the way it was done. I feel it would have been easier to just pull the plug."

About 4:25 a.m. yesterday, McNeill said, a man walked into the main lobby of the hospital, at 110 Irving St. NW, and asked to visit Toye. McNeill said visiting regulations are very flexible for critically ill patients in the intensive care unit, and it is not unusual to have visitors at that hour.

" Her condition was a very, very serious situation," McNeill said. "It takes any family time to deal with that. That is exactly the kind of situation that visiting hours and access to the patient are relaxed, and family members are allowed to be with the patient and see her condition. The family needs our help and support in making the decision they have to make."

According to McNeill, "The decision not to resuscitate a patient is a cooperative one between the patient's health-care team and the family." She would not release the name of Toye's doctor.

McNeill said that the male visitor identified himself to a guard at the main desk as a family member and signed in as "C. Shelton," and that nurses on the intensive care unit said he could visit with Toye for about five minutes in her private alcove on unit 2-G.

There were 10 patients in private alcoves on the unit, separated by glass partitions with curtains, McNeill said. She said the alcoves are arranged in a semicircle around a nursing station where the hospital staff monitors patients' vital signs on electronic screens and charts. There were seven nurses on duty, she said.

According to McNeill, the visitor was escorted to Toye's alcove by Toye's "primary nurse," who remained there during the visit. It was unclear last night if the curtains had been drawn, McNeill said.

During the visit, however, the nurse was paged to respond to an emergency elsewhere in the hospital, McNeill said. "She told another nurse that she was leaving her patient to respond to another code and was turning the patient over to the other nurse until she could return."

The primary nurse came back about two minutes later, McNeill said, and as she walked in a nurse at the nursing station "saw changes in the heart strip and the rhythm of Mrs. Toye and called a code."

The primary nurse went to Toye's alcove to perform cardiopulmonary resuscitation and discovered that Toye had been stabbed, McNeill said. The visitor was no longer there, she said.

Doctors operated on Toye for almost an hour and a half, she said, but were unable to save her life. She was pronounced dead at 6:10 a.m.

Toye was first admitted to the hospital on July 3, suffering from cardiac amyloidosis, a disease of muscle tissue in the cardiac system, according to McNeill. She also had hypertension and suffered two strokes at the hospital.

Neighbors said yesterday that Toye was one of the most popular persons on their block -- the first with a piece of cake, a card, or some money for a neighbor to help buy her daughter's graduation ring.

"She used to sit in her front yard and greet neighbors walking up to church," said Mary Bridgers, who lives two doors away from Toye's house on 13th Street. "She was my best neighbor. We exchanged gifts at Christmas."

Toye, a widow for many years, had helped support her family for 25 years, working full time as a housekeeper for a Virginia family, according to neighbors and relatives.

Yesterday Darrena Shelton, still shocked from her grandmother's death, pulled out a stack of 25 letters from assorted charities to which her grandmother had contributed.

"This kind of mail comes to her in one week," she said. "Anything that came on TV that needed money, she'd sit at the kitchen table, write down the number and, next thing, she'd be out to the mailbox" with a donation.