On a Friday night, late in October, a stranger shot Christian Karotsch in the stomach. He was rushed to Fairfax Hospital and lived for five hours before he died on the operating table.

The day after they buried him, his mother, Liliane Williamson, received a letter from the hospital administrator. It was a form letter, expressing sympathy about the death of her "daughter."

Another form letter arrived a few days later, asking her to make arrangements within 72 hours to replace the 15 units of blood used for her son before he died.

Two weeks later, she received a bill from Fairfax Hospital for the 4 1/2 hours her son was there before he died. The total bill came to $5,107.67.

Williamson remembers well her reactions when the bill came. "I thought to myself, "This is impossible," she said. "I went back to the beginning of the bill and yes, there was Chris' name, but my own name was wrong and so was the admission date."

"They charged me for two operating rooms," she said. "But he died in the first one." There was a charge as well for intensive care unit, for which, she said, he had never had any use.

There were 22 charges for "blood bank products," ranging in price from $12 to $126. There were 15 charges for "blood processing" at $22 apiece. There were 15 charges for whole blood at $25 a unit. Altogether, there were 27 "services rendered," which were listed as being delivered Oct. 24, two days after her son had died.

There were seven pages to the bill. "I kept going through it," Williamson said. "I kept seeing that date, two days after he died, and I kept seeing the blood, all that blood and I yelled, I just really yelled. I said, "My god, this can't be true.'"

In fact, said the hospital spokeswoman, the total bill was not "unusually high for a case like that. Sometimes," she said, "it's a lot more."

Nevertheless, when Williamson called to ask about the bill, a corrected statement was sent to her. The hospital changed the dates, dropped $330 charges for one of the operating rooms, and knocked off a $12 blood bank product. Liliane Williamson hired a lawyer.

In response to a letter from her attorney, Fairfax Hospital recently provided him with an apology for the sympathy letter that reffered to Williamson's son as a "daughter," an explanation of the mistaken dates and a reduced bill that totaled $4,057.67.

With the exception of the extra operating room, the charges were not reduced because any of them were invalid, the hospital spokeswoman said but "because we wanted to avoid troubled . . . We wanted to pacify them. We did it in the interest of good public relations."

"I just don't understand it," Liliane Williamson said in the English that still follows the grammatical channels of her native French. "To me, it doesn't have logic."

But the logic has not been a major role in Christian Karotsch's death or in the days that have followed it.

He was shot on a street in Fairfax County. He was walking along with a friend, the police said afterwards, when a young boy got out of a car and asked him for some marijuana. There was an argument. The driver of the car got out of the car as well. He shot Karotsch and drove away. There have been no arrests.

Liliane Williamson was dozing when the telephone rang. It was the police. Her son had had an accident, the officer said. He was at Fairfax Hospital. He would be all right, Williamson remembers the officer telling her.

Driving to the hospital, she assumed her son had been in a car accident. At the hospital, she learned he had been shot.

She signed forms she remembers, and waited. Everyone she asked said her son would be all right. But she began to be nervous, she said, when an orderly appeared carrying a brown paper bag. In the bag were her son's clothes, and it brought back memories of a friend's car accident two years ago. She remembered such a bag being handed to the mother of the boy who died in the crash.

No one seemed to know anything about her son's condition, she said, until she saw a man standing near the entrance to the emergency room. "I said to him. 'What are they doing,'" she remembers now. "I said, 'What are they doing to my son?' He said, 'What do you think we are doing? We're trying to save his life.'"

At 1 o'clock in the morning, she saw her son for the last time. "He was lying on his side," she said. "He was white, white as a sheet." He said he loved her and she said she loved him too, and then they took him to the operating room.

More than two hours later, a nurse asked her if she was the patient's mother. "She said they were ready to come out," Williamson recalled. "I said, 'my son?,' and she said, 'no, the doctors. They want you to go to the meditation room.'"

"We did everything we could," said the doctors to Williamson. "I said, 'you mean my son is dead." she recalled. "They said 'yes,' and I don't remember much after that."

Later, when the bills came, she sought explanations. There were, for instance, 56 charges for "immunohemotology." Why, asked Williamson, "don't they explain these things on the bill? What is it that they want me to pay for?"

"We assume," said the hospital spokeswoman, "that if a person has a question, they will call us and ask us."

She went as well, she said, to one of the surgeons who had operated on her son to find out more information on how and why he died. "I told him that I would like more information on my son's death," Williamson said. "He asks me if I had even looked inside a chicken. I said, 'I beg your pardon?' He said, 'Well, we are not much different than they are.'"

She asked him also where "all the blood had gone. I couldn't understand what could have happened to all that blood they put in him." The doctor, she said, answered by saying that the blood had gone "all over (his) pants."

"I pride myself on taking the time to be sensitive and doing my best to avoid further pain," said the surgeon, Peter D. LeNard. "Obviously that time, I didn't succeed."

LeNard said he used the chicken analogy "because it's an animal most people are fimiliar with. If you've ever cooked, you've probably seen the inside of a chicken and it becomes easier to explain the anatomical principles involved."

Asked if he had made the remarks about where Christian Karotsch's blood had gone, LeNard said, "I wouldn't have the foggiest idea."

Liliane Williamson is working two jobs now, in part to pay for the funeral and cemetery expenses, in part to keep herself from thinking about her son. But the memories come back when she shows a reporter the room he lived in, filled with the usual brash souvenirs of a teen-aged boy.

"Chris was no angel," said Liliane Williamson. "He like to be the tough guy, he got into trouble sometimes. But he was a bad boy. I guess he was just trying to pack 50 years into the 17 he got." He was tall, she said, and so strong he could lift her off the floor without a moment's strain. On New Year's Day, she said, he would have been 18.