When they told her family and acquaintances that Robin C. Arnold was dead, few expressed surprise.

Her brother Dennis said his sister Denise told him, "I knew it was going to happen, but I didn't think it would happen this soon."

Dennis Arnold said that when the FBI agent told him, "Sit down, I have some bad news for you," he replied, "It's Robin, isn't it? She's dead."

Robert Papaj, a D.C. police detective, said, "I figured sooner or later she'd be found dead, of drugs or a beating."

Robin Arnold, 27, a skinny blond, left Baltimore two years ago to become a Washington prostitute, working, her friends said, seven days a week on the city's streets to support a costly drug habit.

She became the third Washington prostitute to die violently this year in what police say is a series of unrelated killings. A truck driver found Arnold's nude body on June 15 in a remote wooded area of Dulles Airport in Loudoun County. The FBI, which handles crimes at the federally owned airport, is investigating the case as a homicide, according to Special Agent Stanley J. Niemala.

How Arnold got to the woods near Dulles and died remains a mystery.

How she went from being a schoolgirl worried about Friday night dates to being a Washington prostitute worried about making enough money to buy drugs is less mysterious, according to interviews with her family, her friends, her customers and her fellow hookers.

"It's really hard to say what a 'typical' prostitute is, because each one brings her own reasons for being there, her own background. But believe me, prostitutes are not happy people," said Lt. Robert Poggi of the D.C. vice squad, who knew Arnold.

While her friends disagree about whether Arnold was ever happy, there is no disagreement that much of her brief life on the streets of the nation's capital was testimony to the detective's statement and a mirror of the seamy world of Washington prostitution.

The daughter of a Baltimore factory worker and a department store clerk, Arnold dropped out of high school after the 11th grade. Her parents separated when she was young and her mother died when Arnold was 20.

Her father, Harold Arnold, said as he agreed to be interviewed about his daughter: "I hope telling her story keeps just one girl from doing this."

He said with a sigh, "The drugs got to her when she was young." Harold Arnold had to borrow the $200 to make a down payment on his daughter's funeral.

Robin Arnold was impatient; she liked excitement, adventure. While her friends settled into waitress jobs and marriage, Robin came to Washington looking for thrills, looking to escape.

"Robin was always a little on the wild side, really outgoing, looking for something exciting to do," said Brenda Rodgers, a friend from Baltimore.

"She liked dating, she liked dancing . . . . She was always the one who talked you into doing something," Rodgers said.

"She was crazy, always out to make you laugh," said Janet Hurst, another grade school and high school friend.

"She'd do anything goofy, crazy. She was just wild in her own little way."

The jobs her old classmates took bored Arnold, Rodgers said, and she discovered she could make a lot more money go-go dancing and nude dancing in Baltimore.

"She met a lot of people. Whenever anybody had something new and interesting, she would try it," Rodgers said.

"At least once, twice if she liked it."

Rodgers added, "She usually got anything she set out for, but it wasn't anything to speak of but her tiny little instant gratifications."

About three years ago, Rodgers said, "We started going to Washington to get drugs -- they were cheaper, we liked the ride up there. When we first started going there, we would go just to get high for the day, and still come home to Baltimore at night."

Dennis, Robin's older brother, offered to buy the family house from Robin and her sister Denise, and they sold it to him.

"After that they had no place to go back to in Baltimore," Rodgers said, and the drugs were in Washington anyway.

Two years ago, Robin and Denise moved to Washington for good.

For Robin, prostitution was a natural progression from buying drugs in the 14th Street corridor and hanging out there, friends and police said.

"It never surprised me," said Rodgers, a Baltimore housewife. "I used to tell her, 'You're so loose anyway, you ought to get money for it.' "

Word of Robin Arnold's death -- in the form of the newspaper article about the discovery of her body -- was posted in the booking room at D.C. Jail, where women arrested as prostitutes are taken.

Word on the street traveled fast. Washington prostitutes are not often killed, according to D.C. police.

Her once-pretty face changed by a couple of years on the streets, Arnold was usually out on the corner at dusk waving at the cars.

Mostly, she worked Vermont and N streets NW, but recently, other prostitutes said, she had moved farther south, to 15th and L streets.

By the time of her death, acquaintances said, Robin Arnold had been a Washington prostitute for two years, logging five to 15 "dates" a night, earning $250 to $600 a day, and spending $200 to $300 a day on a drug called Dilaudid, a heroin substitute known on the street as "D."

She had been arrested at least 19 times in those two years on prostitution charges, according to court records, and she had been convicted at least seven times.

"Robin was a little moneymaker," said Lisa, a 23-year-old prostitute from Maryland who occasionally shared a cab home with Robin at the end of the night.

"Robin was the kind of girl who woke up and knew what she had to do for that day," Lisa said. "There wasn't any: 'What should I do today?'

"A lot of times she would have a trick come over at 8:30 in the morning, so she could [buy drugs and get] high in the morning to get through that next date."

Lisa recalls Arnold getting out of jail once and coming home. "The landlord wouldn't let her in because she hadn't paid the rent," Lisa said. "She just went around the corner to turn a trick, just going off to take care of business, to get the rent money."

"She was hard not to like," said Clarence Farmer, a friend of Robin's sister. Farmer recalls that he once went to 14th Street a little short of cash, found Arnold, told her it was his birthday and asked for some money to buy a drink.

"She gave it to me," Farmer said, grinning. "And I went back a few days later and said the same thing, and she just kept giving me money for a drink. I finally said to her: 'You know it can't be my birthday every day.' "

"The feeling I always got from her," said Poggi of the District's vice squad, "was that she was a little bit more willing to form relationships with her customers. She spent time talking to them, and she had told me she had a couple of them that came to her on a regular basis."

A problem with being a hooker and a junkie, some police and prostitutes say, is that if a woman is spending a lot of money on drugs, as Arnold was, she is less likely to be giving a lot of money to her pimp.

"He was never getting paid properly while dealing with her," said Lisa of Arnold's pimp, "because she was into drugs."

Poggi said Arnold "was into drugs much heavier and much quicker than most . . . and that made her more aggressive and more active on the street." Arnold tended to be abusive to police when she was arrested, four vice officers said. One officer, Pamela Prather, was blunt: "She wasn't of high caliber; she was a junkie . . . . She was just hooking to buy drugs."

Police and the FBI said Arnold died sometime late June 7, the last time she is known to have been seen alive, or early the following morning. A medical examiner estimated that her severely decomposed body had been lying in the brush a week when it was discovered.

The medical examiner said there were no obvious signs of trauma on the body -- no bullet wounds, no fractures indicating a bad beating, nothing indicative of stab wounds. It wasn't possible to tell if she had been strangled, and tests for drugs remain incomplete.

Niemala of the FBI said she could have died of a drug overdose, perhaps while with a "date" who got scared. The investigation continues as Niemala tries to track down her customers.

Arnold was buried in Baltimore on the first day of summer.

Denise Arnold hugged a sobbing relative and consoled him. "She's better off, she's better off that way," she said of her sister. "She's in a better place."

Dennis Arnold, her brother, told the 52 mourners to remember Robin as the person "who wrote you letters, who sent you flowers she never paid me for. Robin, who used to call you up on the phone and say imitating a loud, enthusiastic voice , 'Hello, this is Robin. How are you?'

"I'm sure if she were here," he continued, "that's what she'd say: 'How are you?' "

The Rev. Carl Townsend of the Govans-Boundary United Methodist Church, who said he hadn't known Robin, quoted the Gospel according St. Paul: " 'To be carnally minded is death, but to be spiritually minded is life.' . . .

"None of us would have wanted Robin to die the way she died," he said, and he paused. "None of us wanted Robin to live the way she lived."

Special correspondent Kevin Spear contributed to this report.