The only candles Mary Larkin burned on her birthday Jan. 23. were the ones she needed to light her shabby, fourth-floor apartment. Her electricity had been turned off two years ago.

Nobody walked down the shadowy, drafty corridor to visit the elderly woman. Her best friend had died three weeks before, her cherished cat Baby a week or two later. She didn't have a cake -- in fact, she had no food, only piles of trash that littered her home.

A week after her birthday, two police officers, summoned by a community worker concerned about the elederly woman, came to see her. They could smell the cat down the hall -- it was wrapped in sheets in her bed, dead and decaying. The officers took Mary Larkin to St. Elizabeths Hospital for the mentally ill.

Mary Elizabeth Larkin, age unknown, squirreled away in a city-owned apartment building, alone, malnourished, confused, depressed by the deaths of those she loved, was, until last week, one of the District of Columbia's estimated 8,000 hidden elderly, the older persons who need help, but have not been found by the city's social services agencies.

They live alone, cut off in substandard housing, not eating enough food, and suffereing from senility, the slow deterioration of the mind that comes with advancing years.

When Mary Larkin's mind is clear, the tiny white-haired woman with cloucy green eyes can remember her childhood in central Pennsylvania. She says she was born there 53 years ago; it was probably closer to 70.

She was the youngest of five. All her brothers are dead now, one sister still lives in Canton, Ohio. As a young woman she moved to Roanoke to work in a department store, then came to Washington to take a similar job.

Here she met Joseph Charles Larkin, an electrician from San Francisco."There was never a sweeter, kinder husband who lived," she said. "I thought when he passed I'd go, too.

"He always called me 'Baby.' I would tell him I had seen a dress downtown that I liked and he would say 'well, Baby why didn't you buy it? You know we have the money'."

They lived most of their 38 years together in the same building, 3500 14th St. NW. They moved in about 30 years ago, when the building was comfortable, clean and all-white.

But 12 years ago, in 1968, riots erupted two blocks to the south in the shopping district along 14th Street after the murder of Martin Luther King Jr.

Most of the handful of whites who had remained in the building through the years moved out. The Larkins remained, in their one-bedroom apartment in the rear of the building.

Joseph Larkin died seven years later -- "I wish the Lord had left him here just a little longer," she said. She was then one of the only two white women still living in the eight-story building.

She was robbed several times on the street while coming from the store -- and once in her apartment.

She retells that story constantly. Two men and a well-dressed woman came to her door. She opened it. They pushed her into the bedroom, hit her in the face and demanded money. She told them she didn't have any.

"I was deathly afraid because I didn't know what they might do," she said in a whisper. "They hit me in the face several more times. It was swollen for a long time," she said fingering her left cheekbone. "Then they just went through the apartment taking what they wanted," several rings and a television set.

Although friendly toward her neighbors, she kept them at a distance. She chatted with them, but never talked about her personal life or invited them to visit. Instead, she was close to only one person, Ruth Grimes, another elderly white woman who lived in an apartment building around the corner on Otis Street.

In early January, Ruth Grimes died. "Nobody would tell (Mrs. Larkin) because we were afraid she would go off," said Elvera McGee, a neighbor.

Mary Larking found out and, as a friend put it, "went to pieces. She was her sole companion. You didn't see one without the other.She just fell apart.

"I saw her a few days later outside the building and I heard her tell someone, 'I don't live here. I'm just visiting.'"

In late January, the friend became concerned about the elderly woman after he failed to see her for several days. He asked the Rev. Annie Woodbridge, who runs a community center next door to the apartment building, to visit her.

"She had no lights, no food and she was very wobbly. She told me they were working on the building and that's why she had no lights," said Woodbridge. She called Pepco and was told that the electricty had been cut off for two years, presumably because her bills had not been paid.

Woodbridge said she then tried -- unsuccesfully -- to get help from the city's Department of Human Resources.

When the elderly woman showed her the head of a cat -- now a skeleton -- a few days later, she called police.

For the next five hours, Officers Andre L. Lewis and George W. Catlett, patrolmen with the 4th District, played social worker.

With Woodbridge's help, they coaxed Mary Larkin out of her apartment, and then took her to St. Elizabeths.

"She is a person that has been overlooked for so long," said Lewis as he waited at D.C. General for her to see a doctor. "Everybody seems to be swept up in the bureaucracy."

"Most social workers avoid a situation like this like the plague," said Richard Artis, director of the city's office on aging.

The social workers have no power to commit a person who needs constant care to St. Elizabeths or to the city-owned home for the aged, D.C. Village. Only the police can do that -- and only when a person presents a "clear and present danger to themselves and their community," Artis said.

Mary Larkin now lives in a locked ward at St. Elizabeths with 19 other elderly persons, who, like her, are disoriented and confused.

The diagnosis of her doctor is that she is suffereing from senility, exacerbated by a poor diet, isolation and the shock of losing first her best friend and then her cat.

Like many elderly people, "as long as everything is stable, it (the brain deterioration) isn't noticeable," said the doctor, who asked that her name not be used. "But when they suddenly lose all the cues that have kept them in touch with reality" they become confused.

They revert to earlier years because "most of them have had happier times in the past, so that's what they remember," the doctor said.

A visitor recently asked Mary Larkin if she had a picture of her husband.

She got up from her chair, steadied her reed-thin legs on her cane, then spent the next five minutes wandering up and down the corridor of the hospital, anxiously searching the blue and yellow walls for his picture. She thought she was still in her apartment.

Later she said, with a touch of frustration, "I don't remember where I live. I'm so mixed up. I hate being this way."