Similarities in the slayings of seven area prostitutes have caused police to consider the possibility that a serial killer or killers may be responsible for the deaths.

On Wednesday evening, the body of yet another woman was found, this time in a grassy area next to a west Alexandria office complex off Dawes Avenue. It was unclear yesterday whether the death of the woman, who remained unidentified, is related to any of the other cases.

The seven prostitutes -- the first was killed in April 1989, the two latest last weekend -- worked along L Street between 12th and 15th streets in Northwest Washington in an area known as "the stroll." All were white women in their twenties. All had blond or light-colored hair.

But for every similarity there also is a glaring difference.

Two of the women were shot in the head, two were shot in the chest, two others were suffocated and one died from a blow to the head. One of the women was found in the building where she lived, at least one was hidden in a sewer, while others appear to have been simply dumped in public places. Some of the women were thin, others were overweight.

"If it is the same {person}, then the same MO {mode of operation} is not being used," said one investigator involved in the case who asked not to be identified.

Still, the similarities must be given more weight than other facts at this early stage of the investigation, said another detective who did not want his name used.

"Regardless of whether they were shot, strangled or whatever, they are all prostitutes working out of the same area," he said.

Said another source, "I wish I could tell you definitely that it's not a serial killer. At this point, I just don't know."

The body discovered Wednesday showed no obvious cause of death, sources said, leading authorities to speculate that the victim had been asphyxiated, as were the last two victims, whose bodies were discovered in Arlington. An autopsy was scheduled for today.

Police have described the woman to downtown prostitutes, and they say she generally resembles a woman who worked there until recently.

Arlington County Board Chairman Albert C. Eisenberg said county residents should not be unduly alarmed by those killings, or the recent slaying of a woman paralegal on a Rosslyn bike path.

"Arlington is and will continue to be a safe and secure place," he said.

Eisenberg said residents should report suspicious activity in their neighborhoods to law enforcement officials.

"There may have been some people in the building where one woman was found who had suspicions about the comings and goings in her apartment," he said.

The investigation of the prostitutes' deaths has been complicated by the fact the bodies have been found in several jurisdictions. Yesterday, police representatives from the District, Arlington, Falls Church and Fairfax County met with Virginia State Police, the FBI and the U.S. Park Police to discuss the cases.

The meeting at the Northern Virginia Criminal Justice Academy in Arlington is the latest in a series during recent months, in which investigators have updated one another and shared evidence in what one detective described as an attempt to "piece together a puzzle."

Several area law enforcement experts say police are studying clothing fibers as well as hair, blood and semen, which could be used for genetic testing.

Police say the pieces of evidence and the circumstances point in many directions. Sources say that there could be one killer, seven or some number in between.

For example, the two women found hours apart in Arlington last weekend died of asphyxiation, and officials believe those deaths are related. District police say that ballistics evidence shows that at least two of the three victims found in the District were likely shot with the same gun.

Each case, investigators say, is a mystery within itself.

In the most recent of the confirmed prostitute killings, the body of Sherry K. Larman, 26, was found Saturday atop a four-story garage on South Highland Street near Columbia Pike in Arlington.

A day later and less than two miles away, the body of 20-year-old Sandra Rene Johnson was found in the Glebe Road apartment building where she lived.

Both apparently were smothered with a plastic bag, one source said. Police say Larman apparently had been killed elsewhere. Larman's body was partly clothed. They would not say where Johnson's killing occurred, or whether her body was clothed when found.

Twelve Arlington police investigators have been assigned to the cases and have been working "virtually around the clock" since Larman's body was discovered last weekend, said a source.

Since the slayings, Arlington detectives have spent the last several evenings in the District interviewing prostitutes, their customers, friends, pimps and acquaintances, and talking with store and restaurant employees in areas that Johnson and Larman were known to frequent, the source said.

Virginia State Police investigators are probing the death of Carolen Marie Wallace, 22, of Forestville, whose body was found Feb. 14 stuffed in a storm sewer along Interstate 95 next to Telegraph Road. Wallace, apparently left in the storm sewer for several days, had been shot once in the head.

The State Police, who have two investigators assigned full time to Wallace's slaying, have conducted nearly 200 interviews. Many interviews have been with other prostitutes who work in the area, said Bob Martin, head of the criminal investigation division for this region.

There are no suspects in the case, he said.

A little more than a month after Wallace's death, a pedestrian found the body of Lisa Colleen Grossman, 29, of Fairfax County, lying beside a boating business in the 800 block of South Pickett Street in Alexandria's West End. Grossman, found only a few miles northwest of where Wallace was discovered, died from a blow to the head. Alexandria police have declined to comment on whether they have any suspects.

The first body discovered in Washington was that of Mary Ellen Sullenberger, 20. Her body was found April 2, 1989, and she had been shot in the chest.

The second body found, on Aug. 12, was that of Cori Louise Jones, 29. She had been shot several times in the chest. Bullets from the gun that killed her, police say, matched those used to kill Roxanne Lynn Johnson, 23. Johnson, who was shot in the head, was found behind a District school on Oct. 1.

A District police source said that some investigators suspect that two people working as a team are involved in the D.C. slayings. The source would not say why.

The D.C. homicide squad has at least one detective working exclusively on the cases, a source said. Arlington detectives collectively spent more than 300 hours on the cases last weekend, a department source said.

Another area killing also being investigated is of a black woman whose bullet-riddled body was discovered May 9 on a residential street in Falls Church.

Falls Church police said the body, which remains unidentified, had apparently been taken to the location after the victim was killed. Police do not know whether the woman was a prostitute.

Officials in all of the police departments say the lifestyle of prostitutes makes their slayings more difficult to solve.

If a prostitute has engaged in sexual activity with several partners in the hours before her death, semen taken from the victim's body, which normally might yield genetic evidence identifying the killer, could be useless to investigators.

The transient nature of a prostitute's life creates difficulties in determining who might be a suspect, some investigators said, or in finding credible witnesses.

"Most homicides are committed by a person who knows the victim," Stover said. "I suspect that the victims did not have a long-established relationship with their killers."

Staff writer Sari Horwitz contributed to this report.