A 65-year-old Northwest Washington woman who police initially thought had died of natural causes was actually strangled, the D.C. medical examiner ruled yesterday, and police are asking for a review of procedures used to determine whether a death is natural or suspicious.

The ruling in the case of Dorothy Redd means that police are now investigating a double homicide--the killings of Redd and her friend and female tenant, Harold Ann East, 53, who was found shot dead in the basement of Redd's row house in Northwest.

Redd's grandson, Terry Leon Boyd, 22, has been charged with first-degree murder in the slaying of East. A warrant was issued for his arrest Sunday. Boyd, who received a dishonorable discharge from the Army in recent months, has not been charged in his grandmother's death, police said. Authorities said the killings appeared to have been motivated by theft. An undetermined amount of money was taken, and some of Redd's rings are missing from the home.

Two women older than 65 have been killed in Northwest since September, one strangled and the other stabbed. Those cases remain unsolved. The other strangulation death occurred about a mile from where Redd lived, and police said yesterday they are looking at all the cases for possible links.

Redd, who had cancer, was found dead in her home, in the 600 block of Hamilton Street, at 10 a.m. Friday. Police initially thought Redd had died of her illness, based on information provided by her family and her doctor. Redd's body was removed from the house and was turned over to a funeral home, which put her body in a vehicle parked outside the row house.

But family members walking through the house noticed a strong odor. Seeking the source, they discovered the body of East in the basement. Police, summoned back, declared the house a crime scene.

In a scene that was horrifying for the grieving family, Redd's body was moved from the funeral car to the medical examiner's vehicle as neighbors and friends watched. Until yesterday, when the medical examiner issued the ruling, relatives did not know the cause of death.

East, who helped care for Redd, died of a gunshot wound to the head. The medical examiner's office is conducting tests to learn whether East was sexually assaulted.

Family members said yesterday they are now dealing with the horror of a slaying and the alleged involvement of their relative, Boyd. Relatives and neighbors also want to know how police could have missed the signs of a homicide.

Monica Gant, a neighbor and friend of Redd, said she pointed out to officials that there was blood in the doorway of the house. She also told them that the carpeting had marks as if a "body had been dragged across it."

"I asked them, "Whose blood is this?' " Gant said, recalling her conversation with fire officials and police. "They just ignored me."

Terrance W. Gainer, the executive assistant police chief, said the department is investigating the episode. Police have also asked the U.S. attorney's office for help in reviewing procedures used in investigating deaths.

"We have had some of the same questions about how we made the decision that her death was a natural," Gainer said. "Those are very fair questions."

Investigations into deaths of the elderly often pose a challenge to police departments. Joe Soos, a former homicide detective in Alexandria who is studying what he calls "gray murders," said the Redd death is a case in point.

"There are probably some elementary things police can do, such as a simple walk through the house to see if there is something on the scene," Soos said. "I see this case as exemplary of the kinds of cases that are not infrequently found in this country and other countries."

Staff writer Martin Weil contributed to this report.