The opening scene of what promises to be a three-month melodrama unfolded here tonight when close to 1,000 people, many of them carrying candles in memory of murder victim Stephanie Ann Roper, came here to demand enactment of laws to tighten criminal sentencing procedures.

Roper, a 22-year-old college student, was raped, beaten, shot and set afire last year; the sentences given the two men convicted of her slaying, which will make them eligible for parole in 12 years, inspired the formation of the Stephanie Roper Committee, which organized tonight's rally.

The crowd, undeterred by biting cold, stood and sat for 75 minutes listening to a long list of speakers, many of them telling horror stories of their own. But the most emotional moment came when Roberta Roper, Stephanie's mother, spoke.

"We have all been made victims by the judicial system that failed Stephanie Roper and failed every member of society," Roper told the crowd in a voice that often quavered and almost broke as she neared the end of her speech. "We have come here to tell our legislature that we will not tolerate unjust justice. We are not here looking for vengeance, but we must be the voice and the presence of the victims who cannot be here."

As Roper and the others made their speeches, a number of legislators, many of them supporters of what has become known as "Roper Legislation," stood to the side saying that realistically it will be difficult to accomplish many of their goals during this session.

"This is the kind of thing that you need two or three years to get much passed," said Del. Dennis C. Donaldson (D-Prince George's), whose daughter Patty knew Stephanie Roper in high school. "But this is a way to start."

Del. Thomas C. Mooney (D-Prince George's), a cosponsor of some of the Roper legislation, saw the situation as analogous to the Mother's Against Drunk Driving (MADD) group that pushed successfully for legislation last year. "When they first came down, people said they wouldn't get much done either," Mooney said. "But they made their voice heard and eventually made progress. That's what these people are doing."

Meantime, the key man in the passage of any legislation, Del. Joseph E. Owens (D-Montgomery), chairman of the House Judiciary Committee, sat in the quiet of a nearby restaurant, saying he would, "take a look at the bills." Owens is being counted on by many legislators to keep much of the Roper legislation from reaching the floor.

The Roper Committee has five major priorities: Eliminating the use of voluntary drugs and alcohol as a mitigating circumstance in a first degree murder; giving a jury the choice only between death or life with no parole in a first degree murder; allowing coconspirators in a first degree murder to face the death penalty; making a victim impact statement mandatory before sentencing and revising the parole commission to give the governor more say in parole.

"We want to make parole something that is earned in an extraordinary case, not a right," Roberta Roper said.

The organizers of the rally, cognizant of the legislature's wariness about the legislation, went out of their way to say repeatedly that the group is not, as committee chairman Vic Pietkiewicz put it, "A vengeance-seeking lynch mob."

Pietkiewicz also told the crowd that the committee will soon present to the legislature a petition signed by 91,000 people favoring the legislation the committee is proposing. Kurt Wolfgang, the committee's legislative adviser, said the committee would meet with key legislators, including Owens, during the next few weeks.

When Owens' committee, along with the Senate Judicial Proceeding Committee, meets in joint session to hear testimony on the bills beginning next month, they will undoubtedly be faced by many of the people at tonight's rally who will remember Roberta Roper's final words to the crowd:

"We will make sure that something good will come of this tragedy. The sadness is that for Stephanie and those of us who have suffered, the price we have paid will have been too high. But please remember what Stephanie wrote in her journal--'One person can make a difference and each one of us should try to.' "