D.C. police officers went to a city-owned rowhouse apartment at least 10 times yesterday in search of a man who had set up a "shooting gallery" for heroin users. But the man, Linwood Thompson, has apparently gone, the police said.

"All we found was some syringes on the floor," said Sgt. Michael Radzilowski of the 3rd District police station.

Thompson, 31, had charged heroin users $1 apiece to use the apartment at 1321 Riggs St. NW. He had described himself as the proprietor of the "shooting gallery," where about 50 heroin users injected themselves each day.

Police said Thompson's furniture - a vinyl couch, two car seats, a mattress and two aluminum chairs - was still in the apartment. "I'm going to ask the Housing Department to take everything out of there," said Radzilowski.

Radzilowski said police would continue checking the apartment for heroin users.

City administrator Elijah Rogers, meanwhile, said "this kind of activity will not be permitted in city-owned property."

Rogers said he will talk to Police Chief Burtell Jefferson and housing authorities "about the activities going on at that property. Following that briefing, steps will be taken to see that the activity is ended."

The rowhouse was acquired by the city in the early 1970s. It will be rehabilitated by a non-profit agency within the next year and sold, according to Saul Finn, a director of the Department of Housing and Community Development.

Thompson was a squatter in the apartment and paid no rent. He had lived in the apartment and run the heroin operation there for two years, ever since his former home, the Whitelaw Hotel at 13th and T streets NW, was closed.

Thompson's Riggs Street apartment was ideally located for heroin users, just a few blocks from parts of the 14th Street strip where heroin can be readily obtained.

Homeowners along the block say they have complained repeatedly about the rowhouse junkies to police and the city's housing department, with no results. Police occasionally arrested persons in the apartment on charges of illegal entry and possession of heroin, but the heroin users continued visiting. Officials at the housing department said they have boarded up the apartment previously, but that heroin users keep pulling the boards down.

Police said the housing department will not be able to board up the outside of the building because a legitimate, rent-paying tenant lives in a second floor apartment used as a "shooting gallery." But the department could board up the door to the gallery, Radzilowski said.

Kwame Holman, a spokesman for Mayor Marion Barry, said yesterday that the housing department would nail new boards to the apartment, possibly today, to keep heroin users out.

"The mayor knows that there is a problem with drug addicts who use vacant houses, including city owned houses," Holman said. "The mayor is concerned about it and will take steps to see that this particular house is secured better."

Barry directed police last week to wage "all out war" on drug traffic along 14th Street, near the "shooting gallery" after receiving numerous complaints from the Logan Circle Civic Association and businessmen on 14th Street.

Police said they did not observe any drug transactions and did not make any drug related arrests yesterday morning or afternoon, although crowds of men and women loitered, as usual, on corners along 14th Street where heroin is sold.

Police attributed the apparent lack of drug transactions to the rainy weather, and also to a parade which increased the level of traffic on the street.