Walking in front of the Southeast Washington apartment building where she lives, a 12-year-old girl said it has been hard for her to forget the April slayings of her neighbors Carolann Resper and Juanita Beasley and their two male friends.

"I'm scared," the girl said yesterday as she returned to her apartment in the building at 2839 Robinson Place SE. "I'm scared at night because someone might come into my house and shoot me and my sister."

Other residents of the building said they, too, are afraid. D.C. police say those fears may have hampered their investigation of the slayings, the largest multiple homicide in the District in more than a decade.

So, last week a special task force assigned to rework the investigation set up headquarters in a two-bedroom apartment in the building where the slaying occurred. The hope was that their presence would allay the apprehensions of the building's residents.

Several veteran investigators have criticized the original police probe of the slayings, saying it was bungled in the hours after the four bodies were found last April 9. All of the dead -- Resper, 26; Beasley, 22; Reginald Harris, 26, and Ronnie Best, 20 -- died of gunshot wounds to the head, according to autopsy reports.

The special investigative team -- four homicide detectives, four officers from the 7th District police station and members of the Repeat Offenders Program -- was appointed after the U.S. attorney's office refused to certify a request for an arrest warrant, saying there was not enough evidence to get a conviction.

A top prosecutor from the U.S. attorney's office, Kathleen Voelker, has been assigned to assist the police investigation.

Police said that they also hoped that the officers' presence might jog residents' memories about details of the hours leading up to the slayings.

"It's easier to talk to people in the neighborhood if we are right there. It just works out better," said one investigator. " . . . So far we've gotten along great with our neighbors."

Fliers asking anyone with information about the killings to contact police at the apartment (telephone 889-9661) were distributed in the neighborhood. The D.C. Crime Solvers program has offered a $4,000 reward to anyone with information leading to an arrest or indictment in the case (telephone 393-2222).

A police source said "some headway" has been made in the investigation. However, most residents of the building contacted said yesterday they are skeptical about investigators' chances of finding new information so long after the killings.

Many residents said they were unhappy and uncomfortable with their new neighbors.

"It feels like we are under house arrest and they are invading my privacy," said a woman who lives next to the apartment where the slayings occurred.

The woman and her husband, who refused to give their names, said police were apparently reenacting the slayings on Wednesday when one officer came into the couple's apartment while another fired several shots inside Resper and Beasley's old apartment.

"I didn't know what was going on at first," the husband said, "then I realized they were trying to figure out if they could hear the shots from my apartment."

"I just put three new locks on my door," said another next-door neighbor, pointing to a row of shiny dead-bolt and chain locks on the door.

"I don't want my name in the paper," the woman told a reporter. "I don't want somebody to come to my door and kill me. I think the killer would come back."

But some residents said the hardest part of the aftermath of the slayings is trying to explain to their children what happened.

"After it happened, they asked my 5-year-old son if he heard firecrackers," said a friend and former neighbor of Resper.

"He knows what happened and he's scared, but my daughter is terrified," the woman said. "We just try to talk about it, and let her know that it was aimed against those folks and she shouldn't feel threatened by that."