A 24-year-old Northwest man was indicted yesterday on murder and rape charges in last year's suffocation killing of his next door neighbor, a U.S. Army captain.

In a 21-count indictment, Gary E. Darby also was charged with burglarizing the home of Capt. Camille DeRose Chapman on two occasions before he allegedly entered the house, at 5403 Seventh St. NW, on Feb. 27, 1984, and killed her.

Another District man, Joseph D. Washington, 19, pleaded guilty last month to second-degree murder in connection with Chapman's death. The 28-year-old Army officer was found with her legs bound and a bag over her head.

The indictment of Darby, of 5401 Seventh St. NW, raised new questions among Chapman's relatives about the thoroughness of the police investigation into three earlier break-ins at her home. Hazel Chapman, the mother of the slain woman, said her daughter had reported the burglaries.

"I called her several times and asked her what the police were doing," said Hazel Chapman, "and she said, 'Nothing, Mom.' "

Chapman said her daughter also said that after the second burglary a detective had helped her board up an area in her ceiling because he suspected neighbors were involved.

According to court records, Darby was on probation for an armed robbery conviction at the time of Chapman's death. In May, Darby pleaded guilty to the attempted burglary and theft of a neighbor's house in December 1983.

"Maybe if they had moved a little faster she would not have gotten killed," said Hazel Chapman.

Police declined to comment on Chapman's statements.

In the indictment, prosecutors did not outline the details of the burglary and attack that led to Chapman's death. When Washington appeared in court last month to plead guilty to second-degree murder in the case, he said Chapman already had been raped by the time he reached her second floor bedroom and that he left after others in the group wrapped a cord around her legs and tied them to a dresser. He said he returned later that afternoon with some of the others to take her brass bed, a mattress and some sheets.

Darby was indicted on several charges of burglarizing and stealing from Chapman's house on the day of her death. He is being held at D.C. Jail in lieu of $5,000 bond for failing to return to a halfway house where he was placed after pleading guilty in May to the other Seventh Street burglary.