Edward Steven Doster, the 20-year-old man who killed his mother and himself at the State Department Friday, led a disturbed, often violent, life, friends and relatives said yesterday. They said he had tried to commit suicide several times and had terrorized his mother, a meek woman unable to control her son.

Arrested several times, most recently June 11 in Alexandria on a charge of beating his mother on May 27, 28 and 29, Doster spent much of his adolescence being shunted from one youth detention home in Virginia to another.

His mother, Carole Doster, 44, "had become absolutely petrified about what he might do to her," said her brother, David Speck, a Northern Virginia district manager for a plumbing supplier.

Carole Doster, who a D.C. medical examiner said yesterday died of a gunshot wound to the neck and multiple stab wounds to her arms and legs, had kicked her son out of her Alexandria apartment after the latest beating and had changed the locks and her telephone number to keep him away, a relative said yesterday.

On May 30, Carole sent an urgent, written communique to the State Department security office, requesting that her son's State Department "dependent's pass" be revoked.

Officials said that the security office had prepared a memorandum on the mother's request, dated Thursday, but that it had not been circulated. The State Department is investigating the delay in processing Doster's request.

It was by using his dependent's pass, police officials said, that Edward Doster was able to enter the building at 22nd and C streets NW without undergoing a search of the canvas gym bag -- in which he concealed a take-down rifle -- or passing through an electronic detection device.

Once inside the building, he went to the seventh floor and assembled the rifle in a restroom there, police said. He then made his way to the offices of State Department counselor Edward J. Derwinski, down the hall from where Secretary of State George P. Shultz was working, killed Carole Doster and then killed himself.

Within hours, the State Department adopted new security procedures that allow only persons with permanent State Department or Agency for International Development identification cards to enter the building without passing through security checkpoints.

Yesterday Speck said he and the other relatives were amazed that "someone could walk in there and do that." He acknowledged that his nephew had been violent. "If it hadn't happened there, it might have someplace else," he said in an interview outside his mother's home in Fairfax County.

Speck said his nephew had been unruly and difficult to handle since he was 3 years old, the year his parents divorced.

Carole Doster, who had been working for the State Department as a secretary since 1969, was "a loving mother, but she was also very meek and discipline was hard for her," Speck said.

"She was like the girl in 'The Glass Menagerie,' " said Jorjanne A. Gausman, a Fairfax juvenile court counselor. "She was so fragile, so unable to cope with a child like Steve."

Edward Doster was a tall, rail-thin man with blond hair, Gausman said in an interview. "He's been trying to kill himself for a long time . . . . "He was not a monster; he was incredibly disadvantaged."

Doster lived with the counselor for a year when he was 13, and he once told her he "just wanted to go home and live with his mother and have a life like it's supposed to be."

Carole Doster could not deal with a child who often used drugs and had once been arrested for stabbing a man who had picked him up hitchhiking, said Speck. He said he believed that his nephew had been in three separate juvenile detention centers in Virginia, including one for the emotionally disturbed.

On Wednesday, Doster was scheduled in court once again, this time in Alexandria Juvenile and Domestic Relations Court to face assault and battery charges for allegedly beating his mother in May.

After she was assaulted, Carole Doster moved from her apartment in the Southern Towers Apartments off Shirley Highway and lived for two weeks at the Alexandria Battered Women's Shelter, according to Ellen G. Gilchrist, coordinator of the shelter.

Officials at the Bowie Race Course said Doster listed a Silver Spring address last year when he applied for a handler's job, but that he could not obtain the required state license.

Chick Lang Jr., a Bowie spokesman, said these licenses typically are denied anyone with a criminal record.

Speck said Doster's behavior was erratic. "He seemed to really be in need of a father figure. Whenever a father figure was around, he was always well behaved and never had a cross word for anyone. But at other times, he was impossible to handle."

Speck said his nephew tried to kill himself by slashing his wrists in one of the detention homes.

When Edward Stephen Doster Sr. divorced his wife, he moved to Florida. Later he mailed a gift to his son on his fifth birthday, Gausman said. "He was elated," she said. "He cut off the return address on the brown parcel and saved it," and later he used it to try to track down his father.

Eleven years later, while searching for his father in Florida, Edward Doster again almost killed himself. Gauzman said he was on drugs and fell into a trash pile, and a garbarge truck scooped him up. Only after a driver turned on the mechanical smasher did he realize Doster was in the truck. The counselor said Doster was severely bruised and believed he limped after the accident.

Almost everything Edward Doster did was a signal for attention, Gausman said. The counselor said that when he was at Hayfield Secondary School in Fairfax, instead of just skipping class by not showing up, he would arrive for attendance and then walk out.

"He's been screaming for help all his life," Gausman said. "He did everything in front of people. He just wanted someone to take care of him."

"I know when he walked into the State Department yesterday, he wanted to be stopped. His mother told him he would. He just wanted attention."