While the number of violent crimes nationwide dropped for the first time in three years, violent crimes in the Chattanooga area rose for the second year in a row, according to the Crime in the United States 2007 report released Monday by the FBI.

Chattanooga’s metropolitan area — comprised of Catoosa, Dade and Walker counties in Georgia and Hamilton, Marion and Sequatchie counties in Tennessee — experienced almost 664 violent crimes per 100,000 residents in 2007, the most since the area had about 611 violent crimes per resident in 2004, according to the report.

“Chattanooga doesn’t have a problem with just random violent crimes,” said Assistant Chief Bobby Dodd, who oversees criminal investigations for the Chattanooga Police Department. “It could be domestic-related, drug-related, gang-related.”

What random crimes occur usually stem from drug activity, he said.

The Chattanooga metro area, which grew by more than 200,000 residents from 2006 to 2007, has a greater crimes-per-resident rate than Knoxville, which has a metro population about 130,000 people larger than the Scenic City, the report shows.

The national violent crime rate was about 467 occurrences per 100,000 residents, data show.

Chattanooga itself experienced 74 more violent crimes, but six fewer homicides, 16 fewer forcible rapes and eight fewer robberies in 2007 than 2006, according to the report. In 2007, there were 11 homicides, 102 forcible rapes and 524 robberies in the city, according to the report.

The Chattanooga Police Department uses the annual data to make comparisons with other departments its size or to track trends over time. But because the report is dated by the time it’s released, the department analyzes its own numbers monthly to keep tabs on what crimes increase or decrease, Chief Dodd said.

“We crunch the numbers closer than what these folks do here” in the report, he said. “We look at crime type, geographic location, times of day (for crime in Chattanooga) and use those for strategic planning.”

The Hamilton County Sheriff’s Department uses the data to determine trends to identify if certain crimes happen at certain times of the year, said Sheriff Jim Hammond, who had not yet seen the report.

Not all crime trends can be curbed, he said. But by looking at numbers, departments can determine where to focus their efforts and who to notify when, for example, copper thieves are targeting catalytic converters, he said.

“Police look at that, and it gives them a chance to warn car manufacturers to be more cautious,” Sheriff Hammond said. “It’s helpful to us when we look at the big picture.”

The FBI cautions against comparing or ranking cities in the report because the numbers do not detail the many variables that cause crime to occur in each location. And because data are self-reported, agencies can choose not to report certain details or may classify certain crimes differently than other departments, FBI spokeswoman Stacie Bohanan said.

“Every city is made up differently. It’s kind of apples to oranges,” she said. “It depends if the population numbers are different. There’s just a lot of different things.”

The FBI examines the data for trends to determine where it can help local and state law enforcement officials create task forces to combat certain crimes that have increased in frequency, such as bank robberies or aggravated assaults, for example, Ms. Bohanan said.

“It gives us a snapshot of what’s going on across the nation in different areas, and it helps you decide what kind of resources you need to assign where,” she said.

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