Shortly after midnight yesterday morning, D.C. Police Officer Deborah Weinsheimer, driving Scout Car 98 in Washington's third district, received a radio call reporting trouble at Apartment 8 at 1340 Q St. NW.

Within minutes, Weinsheimer, 26, who has been a police officer since 1973 and is married to another D.C. police officer, had fired her gun for the first time in the line of duty.

The one bullet she fired, according to the police, killed David P. Leach, 59. He lived in Apartment 7 at 1340 Q street, and, according to police, had fired one shot at Weinsheimer before she shot, him.

Weinsheimer is the second female D.C. police officer to have shot someone fatally in the line of duty. The first was Officer Ilena Saunders of the sixth district who on June 28, 1974, killed Clint Hayes Jr., on a Metrobus. Saunders was cleared by a grand jury of any wrong doing on Aug. 7 of that year. She is still an officer in the sixth district.

Weinsheimer has been placed on routine administrative leave with pay until the case is considered by a grand jury.

The scene of yesterday's shooting is a three-story apartment building. Leach and Harvey Hopson, who occupied the two third-floor apartments, were the only paying tenants - at $100 a month - according to a landlord Henry Williams.

Williams said yesterday that Leach, who was unemployed, had lived in the building two months and Hopson about six months. He said the two were friends.

But it was Hopson, who lives in Apartment 8, who called police and, according to Sgt. Robert Sharkey of the homicide squad said, "Leach had threatened him with a gun."

Weinsheimer, police said, arrived at the apartment building, which is located next to an alley halfway between 13th and 14th at about 12:20 a.m., and climbed the two flights of stairs to the third floor.

Directed to Leach's apartment by Hopson and a women who Williams yesterday described as "Harvey's girl friend," she went to apartment 7, which is located six feet away from apartment 8 down the tiny hall.

Leach opened the door and confronted Weinsheimer with a gun, which he fired once at her, according to police who said she returned fire, striking Leach once in the neck. Weinsheimer was not hurt.

Leach was pronounced dead on the scene by a D.C. medical examiner.

Weinsheimer, who husband Frank rides an adjoining scout car route in the third district, was born and raised in Bethesda, and graduated from Walter Johnson High School. She then attended Wilmington College, a small Quaker college in Ohio.

Although she described herself as "a nonpracticing Quaker," she and her husband were married in a Quaker ceremony.

Three nights before the shooting Weinsheimer had said that she preferred working alone. She was alone in car 98 when the call came yesterday morning because her partner Clarence Black had the night off. A second unit with two officers arrived on the scene moments after Weinsheimer, but too late to assist her.

"I'm not sure why I got into police work," Weinsheimer told a reporter earlier this week in an unrelated interview. "I thought about social work, but there wasn't any money in it. The D.C. police force had some spots open and I decided to try something new and exciting. Now it's old and exciting."

Weinsheimer is scheduled to take her promotional exam in March but she says she hopes to remain on the street in some capacity if she is promoted."It's a lot more interesting out here," she said in the earlier interview.

Although she had been at the scene of several homicides during her career, Weinsheimer, according to her police file, had never fired her .38-caliber service revolver or been fired upon in the line of duty.

Yesterday, Leach's tiny apartment still showed signs of the incident. Several pieces of bloody clothing lay by the door and most of what was left in the apartment had been piled on the bed by police.

The Weinsheimers left Washington yesterday to spend several days in the Poconos where they sometimes go camping.It will probably be at least two weeks before the incident is brought before a grand jury.

"Generally when I get a call I try and let whoever I'm dealing with decide how we're going to handle things," Weinsheimer explained earlier to the reporter. "I let their attitude decide my attitude. I react to them."

For example: early Christmas morning, Weinsheimer stopped a group of teen-agers after the driver ran a red light. Finding them apologetic and sober, she gave the driver only a warning.

"They were embarrassed," she remembered. "And when they started singing me Christmas songs, I felt terrible. I had to give them a break."

Thursday morning, when confronted by David Leach, Weinsheimer had not time to deliver a warning.

As a result she will spend the next couple of weeks doing the one thing she detests most. "Why I am out here?" she said in answer to a question. "Well, for the one thing, I can't stand sitting around the house."