On a Sunday evening last June, at the Church of the Holy Rosary in Upper Marlboro, Roberta Roper stood up to speak to a small group of friends and supporters and for the first time stepped into the spotlight created for her by the unthinkable tragedy that consumes her life.

Two months earlier, her eldest daughter, Stephanie, 22, was raped, savagely beaten, fatally shot in the head and finally set afire by two men who abandoned her mutilated body in a shallow stream of St. Mary's County in rural Maryland. That vicious act stole from Roberta Roper the dreams she had for this child, who she said "wasn't only my daughter, but my best friend."

But it was the judicial system that finally betrayed her, Roberta Roper says, when her daughter's murderers were given life sentences that make them eligible for parole in 12 years. It is that "failure . . . to deal justly with Stephanie Roper," Roberta Roper says, that has compelled her to lead an emotional crusade to toughen penalties in Maryland for criminals like the ones who killed her daughter. She has become the ultimate public symbol of an aggrieved mother.

"I have to speak for Stephanie," Roberta Roper said, turning to her husband Vincent during a recent interview in the living room of their home in rural Croom, Md.

"I know you do," said Vincent Roper, a Navy captain who with his wife has termed their campaign a tribute to the "personal worth of Stephanie Roper."

"I don't have any choice," she said.

Until her daughter's death, Roberta Roper, 45, was a part-time art teacher and a content wife and mother who led a private life centered on her family. She was on the PTA board and worked with the Girl Scouts--"the usual things one's children are involved in"--and she taught Sunday School.

She says she had "strong views about violent crime" before the murder, and thought penalties were too lenient, but she was never one to make her views a public issue. But when she and her family became "victims" of crime, and when the courts failed to give her daughter's killers the "adequate justice" Roberta Roper says they deserved, her life was transformed.

Her determination took her from the parish church last June, where she spoke about the upcoming trials of her daughter's killers, to the state capital and the governor's office, where she channels her pain and anger into a forceful demand for stiffer laws. She still teaches three days a week at St. Ambrose grammar school in Cheverly, but has to prepare her lesson plans in between a schedule of television and radio shows, speeches at local clubs and lobbying politicians in Annapolis.

Public appearances were not a part of Roberta Roper's life before Stephanie was killed. But in the months since, she has polished her public speaking, learned to control her sometimes quavering voice, and steeled herself to debate with critics who simply see her as a distraught, and thus misguided, mother. And she is the guiding light for the Stephanie Roper Committee, a lobby with eight chapters in Maryland and that claims 4,000 members, all demanding changes in the state's criminal laws. Stephanie's own words, taken from her personal journal, appear on committee stationery: "One person can make a difference and every person should try."

Bills proposed by the committee, which may come to a vote in the General Assembly within the next 10 days, would, among other things, tighten parole procedures, eliminate specific references in the law that cite drug and alcohol use as mitigating circumstances in death penalty cases, and allow juries to consider sentencing defendants to life without parole in lieu of execution. Predictions in Annapolis are that one or two of the bills may pass but that most face their biggest opposition in the House Judiciary Committee. Its powerful chairman, Del. Joe Owens (D-Montgomery), has said, "You have to be certain that the problem is the law and not the circumstances of a particular case."

Roberta Roper testified at the General Assembly on Friday for the last time this session. When asked afterward how her day had gone, she sounded tired: "I don't know . . . it just seems like so many times they the legislators don't identify with the problems . . . the balance is still tipped so far the other way," in favor of defendants, she said.

There are times, Roberta Roper has said, when she thinks "Gosh, wouldn't it be nice to resume the life we once had." But she is determined to see to it that something "positive" results from her daughter's death, something that Stephanie would have approved of as her legacy. "There are times when I think, 'Stephanie, you must be leading me,' " Roberta Roper said.

Vincent Roper says his wife has always been a "go-getter," an articulate woman whose father told her she ought to be a lawyer. She exudes a warmth often associated with motherhood, along with her firm handshake and her controlled demeanor. Sitting on the couch in her family room, wearing corduroy slacks and a soft, well-worn sweater, drinking her after-dinner coffee, she is simply, as one who knows her put it, "a nice lady."

Vincent and Roberta Roper were married 25 years ago, after he graduated from the U.S. Naval Academy and she was in her junior year at William and Mary College. Roberta Roper devoted her energies to raising their five children. When her husband was at sea, as he often was, Stephanie, the oldest, would help her out.

In 1979, after the family settled down in Maryland and the children were in school, Roberta Roper enrolled full time at the University of Maryland to finish her last year in college. At commencement when Roberta Roper received her degree in art education, Stephanie helped her with her cap and gown, and mother and daughter shared a laugh when someone confused Stephanie for the graduate.

Stephanie, who like her mother was an artist, was murdered in the early morning hours of April 3, a month before she was to graduate with honors from Frostburg State College.

As the photograph of her murdered daughter flashed on the television screen during a recent appearance on a talk show on WDVM (Channel 9) in Washington, Roberta Roper watched without flinching. When the camera turned to her, she recited the gruesome details of Stephanie's death, including how the killers had chopped off her daughter's hands and "intended to remove her head." Her chilling detachment left the audience in shocked silence. And then, repeating lines that she has said over and over again, Roberta Roper recounted how the convicted men will be eligible for parole in 12 years, while "we, our family have been given lifelong sentences of grief."

Roberta Roper says she is willing to expose her wounds to the public because "I want them to understand that they can be victimized not only by the criminal acts of a Jack Jones the man convicted of firing the shot that killed Stephanie but by the justice system."

Jones and his codefendant, Jerry Lee Beatty, "destroyed our daughter, but they can't destroy us," Roper said. To remain silent after they were sentenced "would have signified acceptance" of their punishment, Roberta Roper said, and neither she nor her husband could do that.

She gets no consolation from legal observers who say that while Jones and Beatty may be eligible for parole in 12 years, realistically they will spend the rest of their lives in jail.

"Okay, so maybe he Jones will never get out, but I don't believe that would be the case if the issue had not remained alive in the public's eye," she said.

While Roberta Roper vented her anguish on Channel 9 a week ago, another parent of a murdered child, Dorothea Morefield, sat in the audience and shared Roper's pain, but not her convictions. Seven years ago yesterday, Morefield's son Richard, then 19, was one of four persons shot to death execution-style in a freezer at a Roy Rogers restaurant in Fairfax County. His murderer is serving multiple life prison terms.

"I know what she's going through," Morefield said in an interview afterward. But, Morefield says, she doesn't believe that she or any other survivor of a crime victim can rationally say what is or is not fair and just punishment.

Across the studio from Morefield sat attorney Burton Berkley, whose only son, David, daughter-in-law and nine-month old granddaughter were stabbed to death in Detroit in January. There are no suspects.

"I want vengeance for my murdered family, by God," Berkley said at one point in the show.

"For God's sake, what are we pussyfooting around for?" Berkley asked a reporter later. "In my mind there's nothing wrong with vengeance."

For her part that night, Roberta Roper used a layman's logic about crime and punishment to spar with judges, lawyers and journalists who accused her--politely--of seeking vengeance and not justice.

She is not afraid of her critics, she said later, because "I don't feel there is anyone who can hurt me anymore." If she has any vengeance, she says, it is directed at defense lawyers who would do everything in their power to get a client off on a technicality and "would feel good about it."

Like so many survivors of victims of crime, the Ropers say they believe the justice system catered to the men who murdered their daughter. Roberta Roper cannot understand why the judge refused to allow the jury to see photographs of Stephanie Roper's battered body, apparently because the pictures were inflammatory. "It was their crime," she says. Jack Jones presented a parade of witnesses to testify about why he shouldn't be put to death for his crime but Roberta Roper says she was denied her chance to testify about her grief and her loss.

Yet, she says, "if you open your mouth, you're being vengeful."

The Ropers had expected the jury that convicted Jones of their daughter's murder to sentence him to die in the gas chamber. And when Judge Walter Haile then sentenced Jones and Beatty to concurrent life sentences--allowing the 12 year-parole date--the Ropers were shattered. "It was almost like a physical slap in the face," Roberta Roper said.

"We have four living children. Our sons sat here on the sofa at 3 a.m. in the morning and they were devastated . . . ," Roberta Roper said during the interview at her home. "So we had to do something. It's terribly disillusioning and destructive for a parent when you have other kids . . . telling them believe in this system, defend it, die for it," she said.

The Roper Committee formally came into being in October 1982 and within four months, its members marched into a General Assembly hearing room with two dozen boxes of petitions signed by 92,648 people demanding tighter criminal laws.

The committee's efforts are an attempt "to prevent a similar tragedy from happening," Roberta Roper said. "I want to be able to tell my sons and daughter that there were defects in the law and we did something to change them."

In the meantime, Vincent Roper says, "I think of all the neat things about Steffie." He has buried the memories of the horrible way she died, he added.

"I haven't gotten to that point yet," Roberta Roper said.