Two women whose bodies were discovered in Arlington last weekend were prostitutes who worked in the District, police sources said yesterday. They were the sixth and seventh prostitutes to be found dead in the area since April 1989.

The body of Sherry K. Larman was found about 9 a.m. Saturday in a parking garage at 901 Highland St., near Columbia Pike.

Sandra Rene Johnson's body was discovered about 5:30 a.m. Sunday in the Country Club Towers apartments at 2400 S. Glebe Rd., where she lived, less than two miles from where Larman was found.

Arlington police described both deaths as suspicious, but said they will not comment on the cases until autopsies of the women are completed today.

Police sources said yesterday that both women had previously been arrested on prostitution charges in Washington.

Prissy Williams-Godfrey, president of COYOTE (Cast Off Your Old Tired Ethics), a group that promotes prostitution, said yesterday that she knew both women.

Williams-Godfrey said Larman, 26, was known on the streets as "Stacy" and often worked on 13th Street NW. Johnson, 20, frequently worked on L Street NW, she said.

Sources said that several Arlington detectives came to the District Monday night to interview women in the area of 13th and O streets NW, part of the city's prostitution strip.

Of the seven District prostitutes who have been found dead since April 1989, four were found in Northern Virginia.

In March, Lisa Grossman, 29, was discovered shot to death outside a building in Alexandria's West End.

A month earlier, Carolen Marie Wallace, 22, of Forestville, was found slain in a Fairfax County storm sewer just south of the Capital Beltway. She had been shot.

The other victims were Roxanne Lynn Johnson, 23, of Baltimore, who was discovered on Oct. 1 outside Ballou High School in Southeast, after being shot in the head; Cori Louise Jones, 29, found on Aug. 12 on an Anacostia street after being shot several times; and Mary Ellen Sullenberger, 20, who was dumped in the street near 12th and L streets NW last April 2 after being shot.

There have been no arrests in any of the killings.

At the time of Grossman's death, police officials in the District and in Alexandria said that there was no known link between the slayings, but that they appeared to be related.

They noted that all of the victims were white women, and that four of the five women who had been killed up until then had worked in the area of 14th and L streets NW, the downtown district in which much of the city's prostitution is centered.

The slayings have had no noticeable effect on the number of prostitutes working on the District's streets, but many say the violence has forced them to be more selective about their customers.

The prostitutes also have begun to take such precautions as refusing to get into customers' cars, or taking their own cars.Staff writer Dana Priest contributed to this report.