The fires were set at suburban homes and retirement complexes, at a dollmaker's shop and a Lutheran church. The targets fit no obvious pattern, and there was no sign of the motives that usually underlie arson: jealousy, revenge or profit.

As community pressure grew to find the person setting those fires, in the Seattle area in 1992 and 1993, investigators got a break. The family of Paul Keller -- a 27-year-old advertising salesman who authorities believe set almost 100 fires -- recognized him in a profile released by investigators and turned him in, prompting Keller to confess.

Now, as fire officials in the District and Prince George's County attempt to find their own serial arsonist, they say the Seattle case is a model for complex fire investigations -- an example of teamwork, legwork and tenacity.

But despite its eventual success, the Seattle arson probe also shows the difficulty of gleaning clues from burned-out crime scenes and the psychological complexity involved in profiling and interrogating a serial arsonist. It shows that the public's help is crucial. So far, local authorities say they still haven't got the break they need.

"It seems that in many high-profile crimes, the thing that gets it solved is a tip from the public or a family member," said Prince George's Fire Chief Ronald D. Blackwell. Any detail can help, he said.

"The things people did not think are important could very well be what works for us," Blackwell said.

Authorities have counted 28 similar fires in the District and Maryland since March 5. Six have been linked conclusively by laboratory tests, they said. The fires have left one person dead and seven people injured. Nearly all of the 28 fires have been set in the middle of the night, at the front or back door of a house or apartment building with residents sleeping inside.

The fires began along the D.C.-Prince George's border, but they later expanded to cover a broader area. Authorities say they seemed to stop suddenly in July, then resumed with three fires this month.

The latest fires, like some others among the 28, were ignited using a container of gasoline and an improvised cloth wick, sources have said.

Those who worked on the Seattle arson case say the arsons there started with unoccupied buildings and homes under construction.

But more dangerous fires followed quickly, resembling the wave of arsons in the District and Prince George's. Some buildings that were set ablaze had families and small children inside. Then, on Sept. 22, 1992, a fire at Four Freedoms House, a retirement home in north Seattle, left three residents dead, the only fatalities in the case.

The fires caused millions of dollars in damage in four counties. Seattle area authorities set up a task force made up of more than 130 investigators. Slowly, they picked up information from witnesses, many of whom saw a well-dressed man near the fires.

"It's kind of an unfortunate luxury. You get to know a little bit more from each fire," Lt. Randy Litchfield, a Seattle fire investigator, said last week.

Eventually, Litchfield said, investigators assembled a detailed profile of the arsonist, based on witness accounts and research into traits shared by many serial arsonists. They believed that he was a young, well-dressed, white man -- probably from a repressive or abusive family -- and that he had a Dodge sedan and a compulsion to set fires.

At that point, Litchfield recalled, the Seattle team was in a quandary: If the team went public with the profile, it might bring in a tip from someone who knew the arsonist -- or it might scare the arsonist underground, delaying a capture.

"The gamble is, you're going to spend everything you have and hope you get something new" in return, Litchfield said.

Going public paid off: Keller was turned in by three relatives, who recognized his compulsions about fires and firefighting in the profile. The family members also knew that he had been in the area of some of the arsons while on business trips, Litchfield said.

Keller had a white Dodge, and he also had conflicts with his family.

Investigators tailed him for six days and carefully choreographed his arrest and interrogation. After arresting him in the early morning, investigators told a groggy Keller that they knew he had set numerous fires, Litchfield said. They also told him that they didn't want to charge him with any fires he hadn't set -- hoping for an incriminating response.

Litchfield said Keller "took the bait, hook, line and sinker." He quoted the suspect as saying, "I set some of the fires, but not all of them."

Keller was convicted of more than 30 arsons, plus three counts of murder for the retirement home fire. His father received a $25,000 reward, which he turned over to victims of the blazes.

Litchfield said investigators later learned that Keller, who had been troubled for years, often set fires after he had been drinking and chose targets for unexpected reasons. Suburban homes reminded him of a difficult childhood, Litchfield said, and retirement homes reminded him of his anger at the death of his grandfather.

If Keller hadn't been caught, Seattle authorities said, they believe that he would not have stopped setting fires.

"I'd be shocked if he had stopped," Tim Bradshaw, who prosecuted the case, said last week, "because things were escalating, in frequency . . . and the harm to human beings."

Keller, now 37, would have to live to be more than 100 to become eligible for release from prison.

Like the Seattle case, the probe into the area's arsons is being conducted across jurisdictions. Prince George's and D.C. fire authorities are working the case with help from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives.

Officials investigating the fires in the District and Prince George's have set up a hotline for tips -- 301-77-ARSON -- and are offering rewards. But they say they are not ready to release a profile of the arsonist, fearing it would focus the public too narrowly.

Investigators have conducted surveillance on several people. Two were being watched at the time that the 27th fire was set, last Monday morning in the 200 block of Quackenbos Street NW. They were immediately eliminated as suspects, sources said.

While authorities track leads and attempt to identify suspects, victims of the fires remain on edge, with vivid memories of their sometimes narrow escapes.

Denise Giles, whose home in District Heights was set ablaze in June, recalled awakening before 5 a.m. because of something that "sounded like the wind blowing through the blinds" of her children's open bedroom windows.

She said she rounded the corner to the living room and thought "that it looked way too bright for that early in the morning." The front of the house was on fire.

Giles, 37, and her family escaped the fire without injury. They moved back into the house about three weeks ago after $30,000 worth of repairs. But she said they have been unable to sleep peacefully.

"Every time the motion detector goes off, I think, 'Oh, God, not again,' " Giles said.

Staff writer Allan Lengel and staff researcher Bobbye Pratt contributed to this report.

Denise Giles shows where an arsonist set fire to her District Heights house in June. The damage to the building has been repaired, but she said her family is still not sleeping peacefully.