She was a frightened parent in a city gripped by fear. She kept her two children inside or warned them about strangers, and got nervous if Arthur, 7, or Monica, 11, asked to ride their bikes, or walk down the street to visit friends.

For 22 months, Virginia Rocker, along with thousands of other parents of young blacks here, had changed their lifestyles, worried for their children as 28 turned up murdered and one remains missing. Now she is breathing easier in spite of official warnings that police have a suspect in only two of the killings, Wayne B. Williams, 23.

"Before his arrest, if the children wanted to go outside, I had to know all the details: 'Where are you going, how long will you be gone?'" says Rocker, an employe of the Environmental Protection Agency. "Now, if they say, 'Mama, I'm going to visit a friend,' I just say, 'Okay.'"

No young black has been murdered here in more than two months, a period that coincides with the time police began tailing Williams, the self-styled music talent scout who sits in Fulton County jail, accused of murdering the two young blacks. Williams maintains he is innocent.

But as rumors of circumstantial evidence reportedly linking Williams to as many as 15 killings circulated in recent weeks, the tension has begun to drift away. Atlanta is no longer a city on edge.

"The load has lifted" since Williams was indicted, proclaims Dan Sweat, president of Central Atlanta Progress, a private planning group of downtown business leaders.

"People are starting to smile. You can sense the mood change at City Hall, at the police bureau, with citizens on the street. You can feel the camaraderie again.A blanket of calm has spread over Atlanta after a very turbulent period."

Yet some officials caution against premature exuberance. "It's important to remind everyone that we have 27 cases in which no charges have been made," Public Safety Commissioner Lee Brown says. "The whole community is delighted we haven't had any more young people found dead. But our work has not stopped."

Even as the city experiences relief, people are asking nagging questions: Has the danger ceased because a man has been charged? Or, is the real killer out there somewhere, taunting the city, letting Williams take the rap before he starts stalking again?

Such questions travel door-to-door in ghetto projects like Bowen Homes."I'm just as afraid as before," says Alberta Love, a laundry worker who lives next door to the family of Curtiss Walker, a child victim. "If Williams did it, I don't believe he did it by himself. I'd feel better if they arrested somebody else."

Love expresses the lingering doubts of many. "I still believe someone else is out there, and he's smart as a whip. The killer knows if he showed his hand now, police might turn Williams loose and start looking for him."

Still the city is taking a "deep breath, when a deep breathe is needed," Sweat says. Tourism officials have launched a $150,000 public relations offensive to reverse a slump of visitor traffic in the big hotels and such favorite attractions as Six Flags Over Georgia theme pack and the Martin Luther King Jr. memorial, a decline officials attribute to bad publicity generated by the child murders.

Where billboards once touted a $100,000 award for information leading to arrest of the killer or killers, they now proclaim: "Let's Pull Together, Atlanta," the slogan of a community relations campaign.

For summer camp at the Thomasville Heights Recreation Center, children no longer show up armed with knives, baseball bats, iron pipes or sharpened sticks, says Jimmy Joseph, supervisor of the city-run day camp for 368 children that abuts a dingy southeast Atlanta housing project frequented by several victims.

Fights have fallen off, too. "We used to have 10 fights a day," Joseph says.

"They were triggered by little things. Somebody touched someone on the hand. The kids had been cooped up so long" by fearful parents," "they just needed to let off steam. Now the few fights we get are from the usual ghetto power struggles, between kids who say, 'I want to be king of this turf."

Bombarded for months by media warnings, children were afraid to venture outside to play when camp started June 8. "They used to say, 'I don't want to play outside, I'm afraid of the snatcher,'" says Octavia Willis a counselor.

Williams was arrested June 21.Now, all across the city, children can be seen frolicking on playgrounds, walking the streets. Police says more children are out past curfew. Many walk home alone, or in groups, rather than wait for relatives to pick them up. They say parents are allowing more independence, dispatching them on errands.

"I used to be so scared, I be shakin'," says Michael Harris, 12. "Now, my parents let me walk to my cousin's house, or to my grandmama's. I get to go to the store by myself."

At recreation centers like Thomasville Heights, where the city has set up Safe Summer '81 day camps for 16,000 children, youngsters no longer line up by the dozens to call home to alert parents of every move. Nor do parents hover outside the centers any longer.

Everyone seems more relaxed; maybe too relaxed, says Camille Bell, head of the Committee to Stop Children's Murders and mother of 9-year-old Yusuf Bell, victim No. 4.

"People want to believe it's over," she sighs. "The individual mentality is, 'I'm not sure Wayne is the one.' But the collective mentality is, 'I sure hope he is so we can stop being scared.' And the behavior coming out of that is that people are becoming less and less on guard and less safe."

Officials agree that much of the euphoria comes from wishful thinking, a need to have the crisis resolved rather than evidence linking Williams to the murders of Nathaniel Cater, 27, and Jimmy Raye Payne, 21. A crime laboratory technician has testified the evidence consists largely of fibers and dog hairs that bore "no significant microscopic differences" from those found on the two victims.

Crime lab technicians have found similar fibers on as many as 15 victims, it has been reported. Investigators say they have traced fibers from Williams' green rug to a small South Carolina textile firm that stopped making such fibers about 10 years ago, a fact that strengthens the value of the fiber evidence, officials say.

But investigators now worry that a medical examiner's failure to rule Payne's death a homicide could hinder prosecutors. The Fulton County medical examiner deemed it a "case of probale asphyxiation," and told reporters drowning could not be ruled out. He listed the manner of death as "undetermined." Police listed it as murder.

So many uncertainties remain, have the murders really stopped?

Some parents, like Robert Lewis Thompson, a groundskeeper for the city water department, still insist on driving their children everywhere. Last week he picked up Stephanie, 9, Anthony, 8, and James, 7, after their day camp let out, though it was only three blocks from home.

"I'm still afraid for them to walk home alone," he said. "They might have the wrong guy. The real killer might be laying low. So I tell them to stay put until I pick them up."

Another parent, Tanya Underwood, worrying about her three children, says, "I have to scare 'em to be careful."

Other youngsters have not completely let down their guard. "I don't think I'll be snatched, but just to be safe I still stay in groups," says Johnny Benn, 14, who hugged his two little brothers close as he waited for his mother, a department store cashier, after day camp.

The karate instructor at Bowen Homes' day camp says the youngsters act blase until he announces it is time to learn how to break a stranglehold, the kind of grip that police believe might have been used on at least half the victims.

And after a white liquor store owner shot and killed an unarmed black customer who threatened him last week, the project came to life, taking to the streets in protest before calm was restored.

"It's still dangerous out on these streets, killer or no killer," veteran patrolman Joe Sutton says.