It wasn't her daughter on the witness stand, but it might as well have been.

The teenager was in pain, recounting for a jury how she had been raped by her uncle, and Veronica Vaughan, her victim advocate, was feeling her hurt.

The girl had cerebral palsy. Her attacker -- the man she once considered her "favorite uncle" -- was infected with the AIDS virus.

"I was afraid to move," the teenager stammered in D.C. Superior Court. "I didn't know what would he do."

Each halting answer seemed to be a struggle for the 18-year-old, who was 17 at the time of the attack and who looked at least a couple of years younger. As she sat in the courtroom that day last year, it took all the strength Vaughan could muster to keep her composure.

"I wanted to cry," Vaughan said in a recent interview.

Hearing about a victim's heartbreak is Vaughan's job, and the job of the 13 other advocates in the U.S. attorney's office. So is staying strong in cases like these.

Vaughan works mostly with children, many of whom have been sexually or physically abused. The cases often hinge on their testimony, and Vaughan must prepare them to relive their ordeals. Fall apart, and the victim might, too.

So Vaughan did not cry that day. And the teenager, who had come to see Vaughan as something of a surrogate mother, soldiered on, sealing the case against her uncle.

In the unpleasant world of prosecuting sex crimes and child abuse, victim advocates such as Vaughan often hold the fragile cases together, prosecutors say. Whatever the other evidence, success often rests on ensuring that the victim takes the stand and testifies credibly.

And no one, many prosecutors say, is better at bringing along victims than the 36-year-old Vaughan, a soft-spoken former social worker who came to the U.S. attorney's office almost five years ago.

"She's just absolutely gifted in her skills," said Assistant U.S. Attorney Sharon Marcus-Kurn.

To talk to Vaughan about herself and some of the cases she has worked on over the last year is to see how difficult and complicated a victim advocate's job can be.

The cases illustrate the depths of human depravity:

A 12-year-old runaway from New York was brought to D.C. to work as a prostitute. Two sisters, ages 7 and 9, were forced to flee their rampaging mother moments before she stabbed their 1-year-old sibling to death. A woman was gang-raped in her home while her boyfriend was held at gunpoint inches away. A father molested his 8-year-old daughter and her 10-year-old sister. And so on.

In each case, Vaughan is at once an ally for the victim and an arm of the prosecution, consoling and coaxing all in the same breath. Rarely is that harder than when a child is called upon to testify against a loved one.

"We'll talk about how they feel about what's been done to them," she explained. Often, "they want this behavior to stop, and we talk about how this can help. We may even say that this is a way of getting help for the person they care about."

The interests of the victim and the interests of justice usually coincide, prosecutors and advocates said. But in individual moments along the way, they can seem to collide, which is what was happening just before the teenage rape victim took the stand against her uncle.

Inside the witness waiting room, the girl was saying that she did not want to testify, that she could not go through with it, recalled Rachel Carlson Lieber, the assistant U.S. attorney who prosecuted the case.

"She was clinging to me," Lieber said, "and clinging to Veronica, saying, 'Don't make me do this.' "

The anxiety was not new. As they often do with nervous witnesses, Lieber and Vaughan had brought the teenager to an empty courtroom a few days earlier in hopes of easing her fear.

But she was still scared, Lieber said, so Vaughan spoke to her: "The calm, steady voice of Veronica was saying 'You can do this. It's going to be hard, but you're so strong, and I know you can do this.' "

And she did. "She was really a very brave young lady," Vaughan said.

Because the uncle was HIV-infected, the girl was put on medication after the attack. She has tested negative for the AIDS virus.

Brave as the girl was, Lieber said, the prosecution would not have been successful without Vaughan.

"I don't think we could have gotten through that trial without her," the prosecutor said. And emotionally, "I don't think I could have gotten through the trial," Lieber said.

Indeed, although she focuses her work on the victims, Vaughan often ends up counseling the prosecutors, too. A lot of frustration, anger and sadness can well up over the course of some of these cases, and Vaughan is always there with a smile or a hug.

"You wonder," Lieber said, "who hugs her."

Sitting in her office off Judiciary Square, Vaughan, who is married, smiles broadly when she hears how the prosecutors have come to depend on her. On her desk are a stress ball, a yo-yo and a bowl of Jolly Rancher candies. Next to them is a framed card depicting five cherubs.

The tiny toy cars and assortment of little dolls on the shelf by the door make the room feel like the corner of a kindergarten class. But the titles on the pamphlets on a shelf next to her desk underlie the seriousness of what happens here: One is "Helping Your Child Grieve." Another is "The Hidden Hurt: Child Sexual Abuse."

The windowless office is where Vaughan meets many of the victims she works with. The first meeting usually comes soon after the abuse or attack occurred, to talk about what has happened and what is ahead. If the case is headed to trial, more meetings will follow, to help prepare for the experience of being in a courtroom. And if the defendant is convicted, this is where the victim and Vaughan will meet to craft a statement to the judge explaining the impact of the crime.

It is a room that has witnessed untold pain. Yet after almost five years, Vaughan seems no worse for what would seem to be the inevitable wear on her spirit. She said she draws strength from God and from the people she is helping.

"I think for me, I just get so inspired, particularly with the kids, that they muster up the strength and courage that they have inside of them," she said.

Around the courthouse, Vaughan sometimes can seem like the mother who is everywhere. She will be sitting on a bench outside a courtroom, helping a little child finish a drawing. Or she will be the one rushing out to comfort a tearful victim who can't bear to hear a defendant deny his guilt again.

Or she will just be the one walking down the hall, holding some small person's hand.

Born in Washington, Vaughan spent the early years of her childhood in Southeast before moving to the suburbs. She grew up wanting to be a pediatrician, but did not think she would be able to manage staying up days at a time.

So she ended up in social work, and for five years she worked in the city's beleaguered child welfare agency, where she saw up close some of the city's most troubled families. She saw how destructive anger could be in a family and came into her current job determined not to let such emotions take control.

With her soft voice and endless patience, Vaughan has the temperament that many prosecutors do not, and for that they are grateful.

"I need the opposite of me," said Assistant U.S. Attorney Cynthia G. Wright, who won a conviction last month in the child prostitution case. "I'm very aggressive. She's very calming."

The case was the first to go to trial under a new child trafficking law, which added to its complexities. At the center of it all was an adolescent girl who had run away from home. When she met Carlos J. Curtis, she thought she had found an adult who cared about her. He offered her food, clothing and shelter. But he wanted to use the 12-year-old, prosecutors said.

No one's testimony would be more important than that of the traumatized girl, the child of an absent father and a crack-addicted mother. "There were just so many issues with that child," said Wright.

Not least of them was the fact that she had been raped while at the city's juvenile detention center. Child protection officials had mistakenly placed the runaway there while arranging for her return to New York.

Overcoming all of those issues would take time and require much attention to the girl's needs. She had not felt the love of an adult in a while, so it would be up to those prosecuting the case to show her she was loved, even as they prepared to put her through a trauma all its own.

At one point, the girl was so overcome with anxiety that she vomited on Wright. "You don't know what it's like to put a kid through one of these trials," Wright said. "It's incredibly stressful for the victim."

Among Vaughan, Wright and the girl, there were talks about music, occasional trips to the library and other sorts of diversions. And there was a trip to a Chinese restaurant in Southeast.

One day during trial preparations, the girl told Wright she wanted Chinese food. So Wright took her to Tony Cheng's. But the girl was craving chicken wings and mumbo sauce. At a downtown spot like Tony Cheng's, the dish wasn't on the menu, and the girl just picked at her food.

So Wright turned to Vaughan and to Tommy Miller, an investigator working on the case. Vaughan and Miller had a good idea where they'd find what the girl wanted.

Just over the Sousa Bridge, on Pennsylvania Avenue, they arrived at a little strip of stores and walked the girl into the Wah Sing restaurant. Soon she was digging into her wings and sauce.

It was a little thing, they said, but the gesture showed her that somebody cared. "She really appreciated it," Vaughan recalled.

Days later, the girl took the stand to testify against Curtis.

On July 2, a jury convicted him in U.S. District Court of sex trafficking and other charges.

Afterward, all Vaughan wanted to talk about was the girl. She had all the reasons in the world to be angry, Vaughan said, and yet she wasn't.

"I just think she's remarkable," she said.

Victim advocate Veronica Vaughan, with the U.S. attorney's office, sometimes uses artwork geared to children to encourage young victims to tell her more about crimes against them so that she can help them prepare to testify.Vaughan, right, with Myesha K. Braden, a trial lawyer in the Justice Department's Criminal Division, at a seminar at the National Center for Missing and Exploited Children in Alexandria.