Curtis Arrington, 23, opened the door of his apartment at 1200 Delaware Ave. SW on Oct. 23, 1975. Four men entered, trying to locate and kill somebody named "Slim," with whom they had a fight the day earlier.

Arrington, a D.C. Superior Court jury was told yesterday said he could not help them find "Slim." So, members of the group, went on to fatally stab him and rape and fatally stab his 16-year-old girlfriend, who had come to the apartment just moments before.

The story of the murders of Arrington and his girlfriend, Lois Ann Davis, was told in testimony by Raymond Paris, 18, who was permitted to plead guilty to second-degree murder in the case in return for his cooperation with U.S. prosecutors.

He testified on the first day of the trial of Larry Hallman, 28, also known as Jack Bumps, who is charged with first-degree murder, armed rape and arson. Two others charged in the case. Warren Peters and Eddie Wislon, previously pleaded guilty to first-degree murder.

Paris testified that the group wanted to locate "Slim" and "kill him." They went to Arrington's apartment, he said because they previously had seen "Slim" there on several occasions when they visited Arrington to "shoot some narcotics."

After Arrington kept insisting that he did not know where "Slim" was, Paris said, the group decided at first to shoot him, but decided against this because a shot would make too much noise.

"I got a butcher knife from the kitchen," Paris said, and the group decided to stab Arrington, who had been tied up in the apartment's bathroom. Paris said they passed the knife from hand to hand, with Peters stabbing Arrington first "two or three times," followed in order by himself, Hallman and Wilson.

As they were about to leave the apartment, Paris said, "I heard somebody knock at the door." He said they opened the door and Miss Davis, who knew the four assailants, entered. Paris testified that they took her into the bathroom to show her the body.

The girl began to plead for her life, Paris told the court. But she was taken into a bedroom where all except Wilson sexually assaulted her, Paris testified.

Hallman, according to Paris' testimony, then announced that "I'm not taking chances - I'm gonna kill the bitch."

Paris said members of the group put a pillow over the girl's face as she lay on the bed. He added:

"Jack Bumps (Hallman) stabbed her in the side and she stopped wiggling. I came down with my knife. Wilson came in with his knife. Peters stabbed her. She was lying limp on the bed."

Paris said that Hallman then went into the kitchen and "put the (stove) gas on" and told him to set the bed on fire. He said the group then left the apartment building, carrying the knives wrapped in a shee

During an opening statement to the jury by assistant U.S. Attorney Mike Scheinenger, Irene Banks, mother of Miss Davis, began crying loudly and had to be escorted from the courtroom.

Judge Nicholas Nunzio refused a request for a mistrial made by Stuart Stiller, the defense attorney, who argued the crying may have prejudiced the jury against Hallman. The trial is scheduled to resume today.