Moments after George Blackburn, 79, and his wife, Lillian, 61, cashed her $102.10 Social Security check in April, three youths rushed into their Northwest Washington apartment and took the money. During the robbery, they beat Mrs. Blackburn and broke her right leg in two places.

Although that attack was the worst, it was not the first for the Blackburns. For at least six months, they have been the victims of a series of beatings and robberies by a band of teen-agers who prey on the elderly in the neighborhood near 14th Street and Spring Road NW.

The latest robbery which left the Blackburns penniless, only added to the miseries they have suffered since last November, when their gas and electricity were cut off because they could not pay overdue bills.

The Blackburns, whose living conditions and bouts with crime were discovered recently by social workers from Washington Hospital Center, said that two young men who frequently plundered their home for money and other valuables began sleeping overnight in a corner of their efficiency unit earlier this year. One moved in with a suitcase, and stayed with the terrified couple intermittently.

"We had no way to force them out," said Blackburn, a thin man, who walks with a crutch, and often scratches the short gray whiskers on his face. "The boys told us they would beat us or even kill us if we went to the police. We didn't want to start no troubles."

The case of George and Lillian Blackburn came to public attention last month when a friend of the couple - Mary Woods - visited their apartment one day and found Mrs. Blackburn sitting on the side of her bed with her untreated broken leg swollen so badly that she could not walk.

Mrs. Blackburn was really pitiful," said Mrs. Woods, whose elderly mother lives in the same garden-apartment complex as the Blackburns. "It had been several days since her leg was broken, but she had no way of getting to a doctor for treatment. So she was just sitting, trying to endure the pain."

Mrs. Woods said she took Mrs. Blackburn to Washington Hospital Center for treatment. Hospital social workers referred the case to social workers at the D.C. Department of Human Resources' office of adult protective services, and representatives from that office visited the Blackburns last week.

"When we first talked with the Blackburns they told us that their electricity and gas were turned off six months ago," said D.C. social worker Delores Roberts. "Because there was no gas, they could not cook their own meals. They had one regular meal a day which was lunch delivered to their door by a church."

Mrs. Woods said she recently gave the Blackburns $20 to help pay the $31.74 gas bill so that the gas could be turned back on. The couple still owes a $67.64 electricity bill. Their phone was disconnected more than a year ago because of overdue bills.

Last Friday, Mrs. Roberts bought the Blackburns a small quantity of food and began efforts to have their utilities fully restored and to obtain food stamps and Medicaid for the couple, who said they had never heard of those benefits before last week.

The Blackburns' apartment, a musty, second-floor efficiency, is littered with piles of dirty clothing. There are no curtains at the windows or carpeting on the floors.

The couple sleeps on an old couch that opens into a lopsided bed. On a scared, gray dresser sits a faded picture of Jesus.On one wall, hangs an outdated calendar from a funeral home.

According to the Blackburns, the walls in their apartment have not been painted since the couple moved in 15 years ago. They said the key to their apartment door was stolen. Now the door remains open virtually all the time.

"We spend most of our time in the apartment just sitting and talking," said Blackburn, who retired 25 years ago from work as a drugstore porter. "Me and 'Mon' would like to go out sometimes. Just walk down the street or sit out in the shade. But it ain't safe. The small children throw rocks and try to hurt us."

"At night we don't have any lights. So we just sit in the dark. We keep on talking till were ready to go to sleep," Blackburn said. "A friend did give us a few candles, but we used them up pretty fast. We used to have a television. But it broke and we didn't have the money to get it fixed."

Blackburn receives a monthly Social Security allotment of $184.90. Mrs. Blackburn, who did odd jobs and house cleaning during her working years, receives $102.10 a month.

Before the Blackburns retired, they said they had visions of pleasant retirement years during which they would be able to pay for a modest, but peaceful existence.

But the reality of retirement and old age has in many respects been a nightmare for the Blackburns, who, for the most part, endure a life that is an endless series of unpleasant experiences.

In Washington last year, metropolitan police investigated 972 reports of crimes against the elderly. Of all the crimes against the elderly, 91 percent were robberies, which police say is the most common form of crime against persons over 65.

"The elderly person tends to be highly vulnerable to such crimes as unarmed robberies, purse snatching and pickpockets because the criminal knows that most older persons are not able to defend themselves," said William Jepson, a police department spokesman.

Sometimes the fear of crime can have an even greater impact on the elderly than the crime itself, according to Andrew Bradley, director of the National Center on Black Aged's project on elderly crime victims.

"Elderly crime victims have a desperate fear of retaliation and harassment following a crime incident," Bradley said. "Their reaction in some instances is like that of a rape victim. They are afraid to report the crime for fear of retaliation. But because they have not reported the crime, they expect to be victimized again."

Metropolitan Police Det. Paul Boska, who took a report from the Blackburns after the April robbery, said the couple told him they did not want to press charges against the young man who was the prime suspect in the robbery - the same person who have moved in with the Blackburns.

"Mr. Blackburn told me he didn't want to prosecute," Boska said. "He said he didn't want to put the man out because the man owed him some money and hadn't paid up yet. With that, we closed the case."

The Washington project is part of a federally funded study of elderly crime victims in eight major cities, including New York, Chicago and Los Angeles.

John Hutchinson, director of elderly persons programs in the Community Services Administration, a sponsor of the national study, said statistics collected in the first year of the survey show that those who victimize the elderly are usually between the ages of 14 and 22.

However, Hutchinson said criminals in this age group do not victimize the elderly any more than they do their own age range.

Hutchinson said the study has found that persons who commit crimes against the elderly study the daily routines of their potential victims.

"They know when the elderly are going to receive their Social Security checks or other income," Hutchinson said. "They follow them to the bank, grocery store or wherever the checks are cashed. And many elderly persons are jumped and robbed before they ever reach home with their money."

"I think we're just lucky that God has keep us living," said Mrs. Blackburn, who can walk on her partly healed leg only by using a walker. "Sometimes I think we ought to get a gun to protect ourselves. But I'm afraid. The boys might take it and shoot us."

Last Thursday, the day when Mrs. Blackburn was to have the cast removed from her leg, she did not have the taxi fare needed to travel to the clinic at the Washington Hospital Center.

So Mrs. Blackburn, who said her leg was itching unbearably, took a butcher knife and a razor blade and began whittling sections of the plaster cast from her leg.

Mrs. Blackburn's effort to free her leg was interrupted by a visit from Mrs. Woods. "She was sitting on the side of her bed sawing away," Mrs. Woods said. "She had the cast down to her ankle and she asked me to help take off the rest. I said 'No.' If you take it of the doctor will have to put another one on."