The fifth floor is a model floor. If Louise Jackson or Perlie Poindexter or Ada Clinksdale or Matilda Berry don't come out, then Marie Reese goes around the hall asking, "Have you seen so-and-so?" until she gets an answer.

With so much "riffraff" around these days, as the building's outgoing president, Lorraine Carter put it, you can't be too careful. And so, day after day, the fifth-floor ladies count on each other just in case, a little neighborhood inside the nine-story, 298-unit Arthur Capper Senior Facility in Southeast Washington, near the Washington Navy Yard.

It was in Apartment 632, just above the fifth-floor ladies, that police on Wednesday found the bodies of George Bailey, 82, and his wife, Maggie, 75. They had been stabbed to death, and police said it took at least four or five days for someone to notice that they were missing.

Police sources initially said it may have been a murder-suicide, but a further examination of the bodies revealed stab wounds, and the case has now been ruled a double homicide.

The killings have frightened the elderly residents and produced much soul-searching in the building at Sixth and L streets SE, one of the largest run by the D.C. Department of Public and Assisted Housing. Beyond that, housing officials said, the deaths also have placed the spotlight on a security problem affecting more than 25,000 District residents living in assisted housing, one caused primarily by people who have no right to be in the buildings.

There was a sense yesterday, on the day after the Baileys were found, that lax security in the building and some residents' disregard for regulations may have contributed to the killings.

Although police sources said there is no evidence that the Baileys' apartment was broken into, many residents maintain that adequate vigilance would have prevented the two deaths.

At a meeting that drew more than 100 seniors, mental health counselors and Jesse L. Jackson to the center's community room, housing officials quickly moved to allay fears. They announced the addition of a second security guard to the building, assured residents that the security company was being monitored and said they were moving with "godspeed" to install security cameras.

But the housing department's acting director, Benjamin Johnson, told residents that security, which he agreed was not as good as it should be, would never be solved by guards alone. As in many public housing buildings, Johnson said many Capper residents contribute to the problem by allowing relatives free access to the premises, in some cases illegally allowing them to move in.

Many of the seniors are taking care of grandchildren whose parents are in jail and who would otherwise have no place to stay, Johnson said. Although not all of these illegal residents are troublemakers, Johnson said almost all crime can be blamed on these temporary dwellers and their friends. "We got some who are as good as can be," he said, "and then we got some that will run over grandma."

The net effect, residents said, is a crime problem that ranges from petty theft to, perhaps, the killing of the Baileys. They are prey to those who know when seniors receive Social Security checks. It is no coincidence, several residents said yesterday, that George Bailey was last seen walking home from a store on the day his check arrived.

John Ellison said he has had two television sets and $50 stolen. A woman recounted how another senior had her purse stolen by a person who entered her apartment using a passkey. And in 1989, in a case that is still talked about, another resident was killed, housing officials said.

This history of crime, referred to by Jackson as part of the District's "long night of terror," explains the need for communal protection, something that already exists on the fifth floor.

"If it's trouble, we have about how many people who will take ladies under their arm?" Berry asked the women of her floor, just minutes after the meeting broke up. "We have Mr. Thomas, we have Mr. Watkins . . . ."