Fairfax County's crime rate plummeted in 2004, according to statistics released this week that show the raw number of serious crimes dropping to the lowest point in 32 years even as the county's population has spiraled upward.

Instances of larceny and burglary in Fairfax -- two of the most common serious crimes as defined by the FBI -- plunged last year. The 14,737 larcenies were the lowest total in the county since 1973, when the population was roughly half what it is now, and the 1,514 reported burglaries were a far cry from the 1970s, when the total cleared 5,000 annually for most of the decade.

Fairfax appears to be bucking a nationwide trend in which crime rates are starting to head back up after years of record lows, according to Chuck Wexler, executive director of the Police Executive Research Forum in Washington, which assists police departments around the country.

"At a time when a number of cities are seeing crime increasing," Wexler said, "Fairfax puts itself in the category of places like New York City and Chicago, which are having record lows. We are seeing the trend changing nationally, with the impact of gangs and methamphetamine. So for Fairfax, it's also notable, given the gang issue. This puts it in perspective."

Fairfax police do not have reliable statistics for gang-related crime. But only one gang-related killing occurred in the county last year -- another one occurred in the town of Herndon -- and there were no gang-related homicides in Fairfax in 2002 or 2003. There have been two killings associated with gangs in Fairfax so far this year.

The number of homicides in Fairfax stayed the same in 2003 and 2004 -- 10 each year -- but the number of rapes and aggravated assaults dropped significantly. Robberies, which rose slightly, were the only increase.

Fairfax Police Chief David M. Rohrer cited a number of crime-fighting strategies the department has adopted in recent years, but he also spread credit to Fairfax's prosecutors, elected officials, county agencies and community groups.

"Our crime rate is a reflection that we are blessed with a good community," Rohrer said in an e-mail. "Residents and businesses truly support our department and they take responsibility in furthering public safety within the county."

The chief cited the auxiliary officer program, the civilian volunteer program and neighborhood watch groups as examples.

The police themselves "have embraced the philosophies of community and problem-solving policing, and we focus on neighborhoods," Rohrer said.

"We have instituted, and continue to improve, a quality crime analysis program," Rohrer continued. The chief said his analysts had created a unique "CompStat" program for Fairfax, modeled after a program introduced in New York that helped police focus their resources on particular trouble spots.

"I believe that we are creative and flexible in addressing problems," Rohrer said. "We use our limited resources wisely and often focus on specific, limited, proactive, targeted enforcement efforts, and will continue to do so."

In combating the rise of Latino gang violence, for example, police commanders have instructed station captains and their squad supervisors to devise ways to attack the gang problem at the neighborhood level. The responses have included increased patrols in gang-troubled neighborhoods, monitoring of at-risk teens, more traffic stops on targeted streets and more Spanish language training for patrol officers.

Fairfax has 1,332 police officers, for a population area of 981,278. (Fairfax police do not serve Vienna, Herndon or Fort Belvoir, which have their own police forces but whose populations are included in standard demographics for Fairfax County, and push the county's total above 1 million.)

Fairfax's ratio of 1.36 officers per 1,000 population is relatively low; cities with a population of a million or more average 3.64 officers per 1,000, federal surveys show.

Montgomery County, the suburban jurisdiction most often compared with Fairfax, has 1.19 officers per 1,000 population. Montgomery's total number of serious crimes dropped 14 percent last year, compared with an 8 percent decrease in Fairfax. But Montgomery experienced 4,500 more crimes than Fairfax, with about 63,000 fewer residents.

The FBI maintains crime statistics for police agencies nationwide, issuing definitions and guidelines on how they should be tallied and submitted. The most serious crimes are murder, rape, robbery, aggravated assault, larceny, burglary and auto theft. Murder, rape, robbery and aggravated assault are categorized as violent crimes; larceny, burglary and auto theft are considered property crimes.

Crime statistics are generally expressed in two ways: as raw numbers (such as the 10 homicides in Fairfax last year) and as a ratio (there were 0.92 murders per 100,000 people in Fairfax last year). Both the raw numbers and the ratios were remarkably low in Fairfax last year.

Fairfax's raw number of 19,160 serious crimes last year was the first time the total has dropped below 20,000 since 1972. The population then was about 497,000, according to census figures, or about half what it is today.

If the number of raw crimes stayed the same, the county's crime rate still would have dropped as the population rose. But with 1,650 fewer crimes in the county last year, coupled with an increase of 10,000 residents, the crime rate fell to 1,952 crimes per 100,000 residents. The crime rate has not been below 2,000 since 1970, the farthest back police records were available. In 1970, the crime rate was more than 4,000 per 100,000 residents.

The amount of violent crime has stayed largely the same since the mid-1970s in Fairfax, between 800 and 1,000 incidents a year. In 2004, the number dropped slightly, but the 1,028 incidents in 2003 were the highest dating to 1970.

Rohrer took note of those statistics and said he was watching closely. "I am concerned about the increasing number of robberies," the chief said, "particularly those we term 'street-level' robberies." He also expressed concern about a possible rise in "new, less traditional crime trends" such as identity theft and other types of fraud, and said "gang-related crime remains a significant concern."

And with Fairfax's immigrant population growing, "I am always more concerned about what I don't know," Rohrer said. The chief said he suspected that many street-level robberies were going unreported.

"I presume that some victims may not report based on language or cultural barriers, or they may not trust police -- unfortunately," Rohrer added. "I also fear that we have significant underreporting of domestic violence for similar reasons."