Within nine hours of Dr. Herman Tarnower's slaying, lawyers for Madeira School headmistress Jean S. Harris, the woman accused of the crime, seized suicide notes she had left at her home on the school campus.

When Fairfax County police arrived at her headmistress' one story brick house at 7:30 a.m. Tuesday, they were startled to discover they were too late.

"When you are expecting a search warrant at 7:30 in the morning, you think you are ahead of the game," said the county's chief prosecutor, Robert F. Horan, yesterday. "But somebody was thinking ahead of us."

That somebody was Joel Aurnou, a well-known criminal lawyer from Westchester County, N.Y. His race for evidence with police detectives is the latest twist in the celebrated slaying of Dr. Tarnower, those best-selling Scarsdale diet book changed the eating habits of nearly three million Americans. The slaying has focused attention on the accused headmistress, a prim, sophisticated woman who managed to keep a troubled side of her life secret from many of her close friends in Washington.

Aurnou said yesterday that he had telephoned a District of Columbia law firm early Tuesday morning -- the day after the slaying -- asking that the notes be picked up. Although Aurnou would not disclose the contents of the notes, police on Harrison, N.Y., say Harris admitted after the shooting that she left suicide notes in her Virginia home.

"We beat 'em [the police] there again. How about that?" Aurnou said yesterday. Lawyers for Harris also managed to outrace police last Wednesday in Westchester County to the Scarsdale post office where they took possession of a registered letter that Harris wrote Tarnower on the day of the shooting.

Aurnou has been subpoenaed to turn over the letter to a Westchester County grand jury next week, but Aurnou said he will fight the effort.

Harris, 56, who has been romantically involved with Tarnower for nearly 14 years, told police on the night of the murder that she had driven from Virginia to Tarnower's home to ask the doctor to kill her. Police also said that Harris acknowledged shooting Tarnower.

The doctor was shot four times with a .32 caliber revolver belonging to Harris. Fairfax prosecutor Horan said yesterday that Harris bought the gun two years ago at Irving's Sport Shop in Tysons Corner.

Harris suffered bruises to her lip, eye and arm in a bedroom scuffle before the shooting. Aurnou, her lawyer, said yesterday that he intends to prove in court that "Harris was the victum of this affair."

"Tarnower never in his life had to fight off this lady. This lady would have died for him," Aurnou said.

In the Washington area, where Harris lived three years since becoming headmistress at the exclusive Maderia School in McLean, interviews with colleagues and friends show that Harris concealed much of her private life.

Although friends in New York say the headmistress suffered for years from a tortuous relationship with Tarnower, a man she loved who refused to marry her, few of the headmistress' acquaintances in Washington ever heard her speak of the doctor.

Harris, a thin, well-spoken blond woman who looks much younger than her age, was an unlikely gun purchaser, friends here say.

Until mid-afternoon last Monday, Harris maintained a strict separation between her professional accomplishments and private misery. Dressed simply in a black skirt and white blouse, she moved crisply through her appointments, keeping busy with administrative work that she'd said would keep her on campus for the next three weeks.

The woman who spent her career instilling high standards in her private school students behaved for much of last Monday as she always had at Maderia. She was businesslike and charming, insightful and reserved. Not until she placed a call to Westchester County, and canceled a late afternoon appointment did anyone notice that she was upset.

None of her colleagues, however, knew why. They didn't know that Harris -- an educator who gave speeches on integrity and advocated "the full involvement of the integral person" in work, family and politics -- had for years sought to give herself in marriage to Turnower. But the 69-year-old cardiologist and friend of the wealthy wasn't interested in marrying anyone and made no secret of the fact.

A close friend of Tarnower's said this week that the doctor sometimes said Harris was "crazy" because she refused to accept his interest in other women. The friend said Harris had sometimes barged into Tarnower's ultra-modern home and searched it for signs of other women.

The image of a jealous, scorned woman as painted by some of Tarnower's friends in New York simply does not fit that of students and teachers who knew Harris in her 28 years as an educator.

According to her acquaintances at private shools in Michigan, Philadelphia, Connecticut and at Maderia, Harris was "an excellent educator," "a fine person," "an enlightened individual," and "a lady always in control." Other than praise, those who knew her there would only say that Harris seemed at times wound too tightly, too intense and prone to get angry over trivial matters. At Maderia, for instance, she temporarily banned saltine crackers and oranges after spotting many discarded crackers wrappers and orange peels on the school grounds.

Jean Harris was born Jean Witte Struven in Cleveland in 1924. She grew up in the wealthy surburb of Shaker Heights and there attended the Laurel School for Girls. It was the kind of exclusive private school for women that Harris has been associated with most of her life.

She was accepted at Smith College in Northhampton, Mass., where she studied history and economics during the way years of 1941 to 1945. ["We gave our bicycles to the Waves and our blood to the Red Cross," the class of 1945 wrote in their yearbook.]

Jean Struven is remembered as an extremely bright, hard-working student who had little time for campus frivolities. "I lived across the hall from her," recalls Enid Hyde, a Washington resident and friend of her former classmate. "She is a terribly fine person, a well-ordered person, so in control of her life."

She graduated magna cum laude, and the following May, married James S. Harris, the dark-haired, handsome son of a socially prominent Grosse Pointe, Mich., family. The Harris' settled in Grosse Point Farms, where they lived in a four-bedroom colonial rambler.

Four months after her marriage, Jean went to work at the Grosse Pointe Country Day School as a teacher of history and economics until 1950, when she quit her job to raise a family.

That year her first son, David, was born. Two years later there was another son, James. Her husband, meanwhile, had taken a job as supervisor at the Holly Carburator Co. outside of Detroit. In 1954, Jean decided to return to the Grosse Pointe Country Day School where she became a first grade teacher.

Bertram Shover, then director of the lower school, remembers her well.

"She was very attractive," he said in a telephone interview this week. "A very pretty woman, who was able to handle both family and school life. She did a lot of writing for the school publications."

One summer, around 1958, Shover recalls, Jean Harris decided to travel, so she went to Russia by herself. When she returned, she gave a lecture on the trip. "She was a very knowledgable woman, very active and socially prominent," Shover recalled.

But in 1964, Jean Harris' well-ordered world began to change. She had lost out on a promotion to become Shover's assistant and in October, separated from her husband.

"I don't think she confined in anybody," Shover recalled. "But I knew she was having family troubles. Very few personal matters did she ever bring up. She was ambitious and she wanted to promote herself."

On Oct. 29, 1964, Jean Struven Harris filed for divorce, asking for the couple's home, custody of the two children and charging her husband with "extreme and repeated cruelty," according to court records.

James Harris agreed to the terms, but claimed his wife was guilty of cruelty also. In March 1965, they were divorced. James Harris -- who died in 1977 -- was ordered to pay $27 a week in child support for each of his sons.

In June of that year, Jean decided to leave Michigan. She had received a master's degree in education from Wayne State University and had been persuaded to seek her doctoral degree. Harris reportedly told her advisers that she must work to support her family.

In September 1966, she moved to Chestnut Hill, a fashionable section of Philadelphia, to become the director of the middle school at The Springside School for girls. She bought a home, raised her sons for the next six years, becoming part of the Chestnut Hill social scene.

It was in Philadelphia, friends speculated, that she met Dr. Herman Tarnower.

In 1972, however, Harris left the Springside School to become the headmistress of the Thomas School in Rowayton, Conn., a private girls school plauged with declining enrollment and a high turnover of administrators. sHarris bought a house in Mahopac, a 45-minute drive from the school and from Tarnower's home in Harrison, N.Y.

According to some at the Thomas School, Harris -- who always signed her papers "J. Struven" -- was not a popular headmistress. She had frequent emotional outbursts, sources said this week, and had difficulty handling the job.

One acquaintance remembers Harris as a "haughty, elegant woman, with a magnificant speaking voice and lovely vocabulary. She reminded me of an actress."

But that same person complained of a lack of warmth. "You could see a hardness in her eyes," he said.

In 1975, the Thomas School closed, a victum of declining enrollment and the trend away from all-girls private schools. Harris was offered a management position at a yearly salary of about $32,500 with the Allied Maintenance Corp. in New York, a firm which supplies janitors for Madison Square Garden and other large buildings.

She worked for Allied for a year and a half before she decided to return to the familiar world of private education. Harris was hired by Maderia in 1977 as the best qualified of nearly 80 applicants, according to a Maderia School official.

Taking a salary cut of nearly $10,000 a year, Harris moved to Maderia's sprawling, wooded campus along the Potomac River.

In three years, many students and their parents say Harris proved herself one of the most capable headmistresses in the school's 74 years. When she stayed on campus on weekends, she left the door to her house open to boarding students who wanted to come and talk to her.

But she spent many of her weekends away. School officials and students say Harris rarely spoke of what she did on those weekends, but Tarnower's neighbors in Harrison say they often saw the headmistress' 1973 Chrysler parked in the doctor's driveway on weekends.

Tarnower, according to friends, dated many women, including his nurse, Lynne Tryforos, throughout the past 14 years. Friends say the doctor told them he never suggested that he would marry Harris.

In the past year, when friends say Harris' relationship with Tarnower was disintegrating, the headmistress maintained her devotion to her job.

On Oct. 12 of last year, in a speech she wrote for Mothers' Day at Maderia, Harris received a standing ovation for her tough stand banning students from the bars in nearby Georgetown.

"Arriving at a value system one can live with and be proud of takes one down a tortuous road," she told Maderia parents.

Yesterday, the headmistress' lawyer said that in recent weeks Harris's private agonies had begun to affect her work. Still, Aurnou said, those around Harris probably did not realize she was suffering emotional problems.

"Being around her last Monday," Aurnou said, "was like standing next to a burning building and wondering whether it was warm."