DISTRICT OF COLUMBIA police officer Lina Saunders is living in a small two-story row-house near the Kenilworth Aquatic Gardens in Southeast these days. There is no screen or glass in the front storm door and the plot of land between the house and the street is nothing but dirt. Her tiny, dark living room is cluttered with furniture moved from the home in Maryland that she sold last October. She says the house she is living in is a temporary stop. Someday soon, she will move back to Maryland, and someday soon, she says, she will finally put her daughter in an institution.

This time, says Saunders, she won't back down. She has finally realized that she can't do it any more, that the price she is paying and the price she is extracting from the lives of her sons are too high. She has finally realized there is nothing more she can do for her daughter. "I've run out of reasons for keeping her home," she says. "It's better for her and for all of us if she's institutionalized. I've learned to accept it now that things aren't going to get any better.

"It's better to have her institutionalized than to have her home every day, wishing she was dead or she was going to die. That's the point it's gotten to now."

Her daughter, Brenda, is 13 years old now. The premature child was in D.C., General Hospital seven months after her birth. "One day they called and said come over. Her head was growing faster than it should. She had complications on top of complications. She had meningitis, colds, pneumonia. We went through that stage where she stayed on the critical list."

Lina Saunders leafs through her photo albums and pulls out pictures of her infant daughter on the day she came home from the hospital. The child is small with a disproportionately large head. There is the photo of Lina holding her daughter, standing up proudly, a tall, handsome woman, cradling her baby on her hip.

"At that time, you think things are going to change. I was living in my little dream world, hoping things would be better," says Saunders. "Now, I've learned to accept things the way they are. I know no changes are going to be made. She'll always be the way she is."

Brenda is profoundly mentally retarded, blind, spastic and hydrocephalic-that is, suffering from an accumulation of water around the brain. The child is immobile. "We have to change her and feed her. We blend all her food. She can't do anything," Saunders says.

Lately, says her mother, the child has become moody and makes crying sounds during the night. Saunder thinks her daughter may be suffering some sort of arthritic pains. Rain disturbs the child deeply. She gives the child Tylenol and phenobartbial, but is wary of addicting her.

Lina Saunders came to Washington in 1961 from Topeka, Kan., to care for her grandfather, and ending up living here, graduating from Fairmont Heights High School, working as a waitress, baby-sitting, cleaning at Howard University, until her marriage in 1965. Her first child, Shawn, is 14 now, and her third, Richard, is 11. Her marriage lasted five years, and after that she was on public assistant until she became a police officer seven years ago.

She earns about $18,000 a year now, better money than she could earn doing things she would rather do. For nearly five years, she lived with relatives in her house in Maryland, and her sister-in-law took care of Brenda. That arrangement disolved last July, and since then, Saunders has had to rely more and more on her sons to care for their sister.

She says she could never manage without the help of her sons, and when you hear her talk you realize she is absolutely correct. The enormous challenge of caring for a child who is so profoundly disabled is compounded by the fact that as a police officer Saunders works rotating shifts-sometimes working midnight to dawn, sometimes days, sometimes late afternoons and early evenings.

This week she is working days. "I leave the house at 5:30 or 6 o'clock. I set the alarm for the kids so they wake up at 7 a.m. Shawm will get up and wash her up and get her dressed . . . Richard comes down and boils water for her cereal. Then they lay her on the bed and he feeds her," Richard cleans up her face after feeding her, and then Shawn brings his sister downstairs into the living room and puts her in a chair and goes to school.

Richard stays with his sister until the bus comes to take her to Sharpe Health School, a public school for severely handicapped children. The bus is supposed to pick her up at 9 a.m., but sometimes it doesn't come until 9:30 or later, and sometimes not at all, says Saunders. When that happens, richard stays home from school.

Richard and Shawn are present at the interview. They listen to their mother, nod in agreement with her, tell a joke, serve good coffee. When she tells them to do something, they do it. They are doing far more for their sister than most parents would dream of asking kids to do, and yet they don't seem to resent it. "They just do it automatically," says their mother. "She's always been with us and there've always been things to do, and they just pick it up. See, I don't want it to get to that stage where they resent her or me."

And that is why she has finally decided to put her daughter in an institution. "All along I've been opposed to having Brenda placed, but she's getting older now. She's more of a hardship on the boys. They're constantly cooped up in the house."

There was a time last July when Saunders fell apart. She calls it her breakdown. She was put on leave for a week, and it was during that period she reached the decision to institutionalize Brenda.

"I have dreams about she'll get better, and then I think, why don't she go ahead and die, and then I think, Lord have mercy, how could I think something like this. . . . I hate my thoughts about this death wish but they're there constantly now. I don't know if it's because she's 13 and she's supposed to die, or just that things are the way they are. At first I was just hiding them, covering up my deep-down hate feelings. Now I've learned to accept it."

Saunders says people ask her how she copes. "I say you just do what you have to do." She has friends she can talk to, other policewomen who help her out at times. Occasionally she takes nerve pills. She used to drink but says she found that doesn't help. Right now, she says, "I just have to be strong for everybody. I can't collapse. Not yet. After everyone else gets straightened out, well, I'm just going to lie down.

"Brenda has all my love. She's had all my care but there's nothing else I can do for Brenda."