The latest sign came Sunday, when her family returned from a weekend trip to find the mailbox torn off its stand and garden flowers stolen from their Owings Mills rancher. But even before then, Christina Pollikof knew it was time to go. Unfamiliar teen-agers were playing on the trampoline out back and throwing apples at her dog.

It didn't matter that this was her home of three years, that she and her husband invested hundreds of hours fixing up the place. Fearing for her safety, Pollikof wouldn't look outside the window anymore. And fearing for the well-being of their 14-year-old daughter, Pollikof and her husband decided it was time to leave the neighborhood.

"It was not like this when we first moved in, but it's really gotten bad within the last year," Pollikof, 35, said Monday, as she swept the street outside her home on the Reisterstown line. "The neighborhood is going down."

Many of the residents who came in droves to this rapidly growing community in northwestern Baltimore County to escape the problems of Baltimore and other urban areas express concern that the crime has followed them.

They worry when they read newspaper police blotters that regularly report crimes including burglaries and automobile thefts.

Even more worrisome, they say, is a string of six killings since last summer, including the fatal shooting of a burglary victim in February, a drug-related shooting at Owings Mills Mall in December and two killings this month.

"If anyone had any misperceptions that the problems of the city stop at the city line, it has blown the lid off," Del. Bobby A. Zirkin, who represents the area, said of the crime. "Things that you don't hear about in the suburbs are moving out" to Owings Mills, he added. "People are concerned. It's a shock."

To be sure, not all residents complain. The leader of Tollgate's community group said his Owings Mills neighborhood suffers from nothing more than occasional graffiti and teen-agers walking down the middle of the road.

And Owings Mills remains safe for most, Baltimore County police say. The recent killings were not random acts of violence. They involved people who knew each other and often were out-of-towners, authorities say.

"It is a stable, safe neighborhood," Bill Toohey, a police spokesman, said of Owings Mills. "It has crime -- every place in America has crime."

But crime once unheard of in Owings Mills is creeping into its neat rows of townhouses, balconied apartment complexes and spacious mall.

On July 10, a 31-year-old resident of an unlicensed assisted-living apartment on Appleford Circle was arrested in the killing of his caretaker.

The day before, a 42-year-old woman was found fatally beaten in the basement of her Kendig Mill Road home. A week later, her husband committed suicide in the home. The woman's death remains under investigation.

On Tuesday, an 18-year-old was sentenced to 15 years in prison in the fatal shooting of Kevin Garmzaban, also 18, a former high school wrestling standout, during a botched drug deal at Owings Mills Mall. Earlier this month, a 16-year-old youth pleaded guilty to shooting Garmzaban and was sentenced to 25 years in prison. Both defendants were from Baltimore.

Police statistics show some offenses are on the rise. There were 28 home burglaries during the first half of this year, more than double the number during the same period three years ago. And there were 56 automobile thefts from January to June, a dozen more than during the first half of 1999. Robbery rates remain constant.

Several residents interviewed this week said the combination of high-profile violence and petty crime has started to trouble them.

"It does seem like it's getting closer and closer," said Lawrence Hicks, who lives several blocks from where Sheryl Anne Purpora was found beaten in her basement, a plastic bag over her head.

"It makes you change the way you used to do things," added Hicks, a 38-year-old warehouse worker, as he washed his car outside the Kendig Drive townhouse that he bought seven years ago. "You don't leave your doors open like you used to anymore. You watch more who comes in the neighborhood now."

Noel Levy, an Owings Mills resident who is running for County Council in the 4th District, said he often hears complaints about crime while canvassing for votes door to door.

"Something has changed," he said, "and I think people are kind of puzzled and surprised. They don't know what went wrong."

The unease has marred what most residents still describe as idyllic suburbia, a community of shade trees, winding streets and abundant shopping opportunities that is a 25-minute ride from Baltimore.

Twenty years ago, Owings Mills was mostly country. But county officials designated it and White Marsh as growth areas; subdivisions, commercial strips and office towers followed. During the 1990s, the population of Owings Mills more than doubled to more than 20,000. Community activists, politicians and county officials partly attribute current crime to that growth.

"When you bring in more people, you bring in more businesses, you bring in more crime," said Vicki L. Almond, president of the Reisterstown-Owings Mills-Glyndon Coordinating Council, an umbrella group of area organizations.

Elise Armacost, a spokeswoman for the county executive, said county leaders are "working to address" growing pains in the two growth areas through transportation, school and public-safety projects.

"The fact that so many families want to call Owings Mills and White Marsh home shows that these are successful communities," she said. "They are not perfect; no community is."

Community activists and leaders point to the 11 group homes in town as another cause for concern.

The state needs to watch foster homes more carefully, while the county should devote more resources to the police and regulate growth more carefully, community leaders say.

"When you grow an area so quickly without the requisite planning, you're begging for trouble," Zirkin said.

The state, following the recommendations of a task force that studied problems at group homes, is beefing up its licensing and monitoring efforts.

The county Police Department is adding a new precinct and building a $4.5 million station just north of Owings Mills.

"This is a direct response to the increased calls for service," said Toohey, the police spokesman. He emphasized that Owings Mills does not suffer from the systemic social problems that cause crime in inner cities.

Calvin L. Reter, past president of the coordinating council, has noticed more broken windows and graffiti and says residents must become more involved in addressing crime.

"We can't expect the police alone to do something without involvement from the community," he said.

But misgivings trouble some residents so deeply that they would rather move out than pitch in.

Stacey Carneal, 30, and her husband have thought about leaving their townhouse of six years. She doesn't go to the local Metro station for fear of who may be waiting there.

"Most likely, we're going to be moving out of the neighborhood in the next two, three years," Carneal said, partly because they want to live someplace less developed. But it is also, she said, "because of the crime."

Sun staff writers Andrew A. Green and Dennis O'Brien contributed to this article.