It was Christmas weekend and Karen Ranfone was afraid for her children. Despite her parents' reassurances and the comforting nostalgia of her childhood home in Little Falls, N.J., the feeling would not go away.

Karen Ranfone's thoughts, she recalled, kept turning back to her two-story frame house in the Del Ray neighborhood of Alexandria, where her estranged husband and young son and daughter were, for the first time, celebrating the holidays without her.

"I was depressed all Saturday and Sunday," she said. "I had a real horrible feeling that something had gone terribly wrong."

It had. On the afternoon of Dec. 28, police found Anthony John Ranfone, 36, the Ranfones' 4-year-old son, David, and their 7-year-old daughter, Christina, dead in the family's aging Datsun B-210, which was shut up in the garage behind the house at 17 W. Caton Ave.

All died of carbon monoxide fumes either on Christmas or the day after in what investigators ruled a double murder and suicide. There were no signs of struggle. In fact, Christina had curled up with a pillow in the back seat as if she had decided to take a nap.

"In my wildest dreams I never thought he would do anything like that," 32-year-old Karen Ranfone said last week, her eyes swollen from tears. "I felt like I didn't know him. I lived with him for 10 years and he was a stranger to me."

Tony Ranfone, it turns out, was a stranger to just about all those who thought they knew him. A slight man with a shock of dark hair trimmed closely around his ears, a mustache and an easy, familiar manner, he had suffered bursts of extreme behavior from the time he was a teen-ager, fits of depression, moodiness, paranoia, tantrums. He was hospitalized after a mental breakdown in 1977 and took drugs to control what doctors diagnosed as a manic-depressive disorder, severe mood shifts from high to low spirits.

Ranfone's oddity came and went, however. His charm, intelligence and assertiveness overshadowed it. And though his wife says she sensed that his disturbance was deep, within a month of the tragedy he inflicted, a city social worker, Alexandria school officials and even Tony Ranfone's own psychiatrist did not believe that he was a danger to himself or those around him. Ranfone was a man secretly unable to cope--and a man unable either to find or accept help so that he might.

"An all-American family," one neighbor called the Ranfones. "A great guy," said a friend of the man who killed his own children. "It certainly was a surprise to those who knew him," said Brian M. O'Connor, the attorney who represented Ranfone in his divorce and custody fight with his wife in Alexandria Circuit Court. "Perhaps he was conning us a bit in retrospect. Nobody had any indication that any of this would happen."

Unexpected or not, the deaths left lingering questions. Karen Ranfone and her family criticize the psychiatrist, social worker, police and school officials who discouraged her from taking the children only days before they died. Indeed, Karen Ranfone blames an entire legal and bureaucratic system that she believes should have identified the deep sickness she sensed in her husband.

"It would be hard to blame any one individual," said Susan Dunn, a friend of the Ranfones and a Fairfax County mental health therapist. "It relates to our own society and to what we have come to accept as acceptable behavior. "

Karen Ranfone met her husband in the trendy Bibliotheque pub in Boston in 1972. She worked as an electric appliance company customer service representative in Boston and he attended school at the the city's Museum of Fine Arts. "The first night he met me he said he was going to marry me," Karen recalled. "It turned me off."

But something about Tony attracted her. "I felt he needed me," she said. And though Karen said she did not then love Tony, she was ready to begin raising a family. So on Sept. 3, 1972, about a year after they had met, they married on a 10-acre Annandale, N.J., farm owned by a friend of her family and moved to Alexandria, where Tony had taken a job as a illustrator for the U.S. Army at Fort Belvoir.

Tony had told her nothing of his history of mental extremes and during their courtship she chose to treat his moodiness and depression as artistic temperament. Soon after the wedding, however, she came to believe that he was deeply disturbed

"The first year was the most unhappy year in my life until this year," she said. "He was a total zombie. He was there and not there." He would go for hours without talking, watch TV in the living room from the time he came home after work until he went to bed, Karen recalled. He would turn the volume way up so he could hear it even while eating dinner in the dining room. He spent his spare time painting and drawing in solitude. While she enjoyed going to museums or out to dinner, he wanted only to stay home or go to bars alone and buy drinks for strangers whom he would then sketch.

Karen said she learned from her husband's relatives that he had been troubled with spells of depression since his teens. And though Karen said her husband rarely spoke about his time in the Army in Vietnam in the mid-1960s, O'Connor, his attorney, said Tony had often been depressed then. At one point, O'Connor said, the Army diagnosed Ranfone's mental condition as paranoid schizophrenic, a serious personality disorder that O'Connor called a misdiagnosis in Ranfone's case.

"I attributed his behavior to a bad temper," said Karen. "I tried being understanding and patient." She said she believed she could help him learn to enjoy life and leave his moodiness behind. In 1974, Tony took a job as an artist for the newly formed Federal Energy Office. At work, he earned a reputation as a talented, though sometimes brooding, artist.

His best-known project was the creation of "Energy Ant,"a cartoon character aimed at teaching grade school children about energy. Over several years, Ranfone developed coloring books, posters and stories depicting the exploits of Energy Ant, a stick-like character that Karen said was a composite of physical traits from herself and her daughter.

Yet, while he was successful at his work, his moodiness continued. In the fall of 1977--at about the time Tony was increasingly upset because the Energy Ant series was being discontinued--Karen decided her husband was "out of control."

"Christina and I had gone out to buy a pumpkin and apples," she recalled. "It was getting to be close to Halloween. While we were out, we had stopped to give an old woman a ride. I thought it was funny at the time and mentioned it to Tony. He said the Communists were after me and the old woman was a Communist, too. He said they needed information he had."

Ranfone placed a three-foot-tall painting of a soldier on his front lawn, telling anyone who asked that it was guarding his home. "It never dawned on me that he was mentally ill," Karen said. "I was so stupid."

In the days before that incident, Karen said her husband had stopped eating and sleeping. "He just talked," erratically jumping from subject to subject, she said. Frightened, Karen called her father, who flew to Alexandria and told Tony they were taking him to a secret anti-Communist meeting. Instead, they went to the Alexandria Hosptal psychiatric unit, where Tony's condition was diagnosed as manic-depressive.

When he returned home a week later, Karen said her husband's behavior had vastly improved. He started visiting a psychiatrist for regular sessions, treatment that lasted off and on for five years, Karen said.

"For two months it was wonderful," she recalled. "I was looking forward to him coming home, and I was falling in love with him."

A few months after his release, however, Karen said, her husband was acting strangely again--preferring to spend his free time in bars, drawing impromptu sketches. Yet, Karen said he always worked hard at being a father, often brought the children gifts, played games with them. He never spanked the children or mistreated them, she said, and he always tried to be a good father.

But finally, after a period of deep depression, heavy drinking and threatening behavior by Tony, Karen took the children, left home and filed for divorce on Sept. 2, the day before her 10th wedding anniversary. She said her husband pleaded for a reconciliation and at one point accused her of only wanting "these beautiful children." He told neighbors he would never give them up.

Two months after his wife left, Tony attempted to kill himself by taping the house's windows shut and turning on the gas oven. Ranfone's psychiatrist called the attempt a "suicide gesture," O'Connor said, citing court testimony.

The children went to visit their father for Thanksgiving, but when the holiday ended he refused to return them to their mother. By early December, Karen had told her friend, mental health therapist Dunn, that the children were with Tony. Dunn recalled that she believed Tony was deeply disturbed, so she phoned the Alexandria Child Protective Services, which visited the children and told her they were not in danger.

Soon afterward, Karen and her father drove from Little Falls to Alexandria to "kidnap," as she put it, her children. They picked up the boy from his baby sitter, but an assistant principal at the girl's school, Mount Vernon Elementary, resisted when Karen asked to take her daughter.

Meanwhile, Ranfone arrived at the school, blocked his wife's efforts and after an angry scene left with the children. Police who arrived refused to intervene, Karen said. Spokesmen for the Alexandria schools and the Child Protective Services declined comment on the matter.

At a Dec. 22 custody hearing in Circuit Court, Ranfone's psychiatrist, who could not be reached for comment, testified that Ranfone was fit to take temporary charge of his children. Karen agreed to allow them to stay with their father through Dec. 26, though she said she did so reluctantly. "This poor man," she recalled thinking. "What's a couple more days going to matter?"

Days later, Tony Ranfone left a piece of ground beef thawing on the kitchen counter in his house, ran a vacuum cleaner hose from his car's exhaust pipe to its interior, and with his children climbed inside.

He was a man who had once told his wife that he saw life as a continuous mountain climb he didn't want to make, and whenever he managed to scale a peak, all he would ever find were more formidable mountains before him. "It's hard for me to understand that view, because we were exact opposites," said Karen Ranfone. "He was utterly unhappy. I don't think he was ever happy like you and I think of happiness."