For the first time in several years, the number of crimes in Scottsdale rose slightly in the first six months of 2011 compared with the same months in 2010, according to the latest records from the Scottsdale Police Department.

Crime in Scottsdale has been falling for the past few years, but from January to June, the number of crimes rose about 1 percent.

When numbers are low, as they are in Scottsdale, the slightest rise in a category can cause a large jump in percentage change. For example, this year there have been 63 robberies, compared with 50 last year - a 26 percent increase.

"One reason the robbery numbers have increased is due to many of the bank robberies being committed by serial robbers," said Assistant Police Chief Sean Duggan, who oversees the department's investigative services.

"Crime in Scottsdale has steadily decreased over the past decade. Even though we've become a smaller workforce over the past few years, we've been able to leverage technology and maximize advances in crime-prevention strategies, community support and regional partnerships."

Police officials meet weekly to look at crime numbers and talk about trends.

"We look at persons and places," police Cmdr. Scott Popp said. "Are there people committing multiple crimes? We look at the same thing in the city. Is there one address that seems to have a high number of calls per service? Is it a residence bringing a crime element to the neighborhood?"

That is the case many times, Popp said: one or two people tied to multiple cases. That's when the department's repeat-offender unit, which targets career criminals, is called in.

Scottsdale also shares information regionally through the East Valley Fusion Center, along with a statewide center run through the Arizona Department of Public Safety.

"Those regional partnerships are essential," Popp said. "The broader perspective allows us to see whether this is one minor incident or a person preying on more than one person in other cities."

Other times, the crime-number analysis is combined with different types of community outreach. In 2010, the department saw higher numbers in reported rapes than in previous years. A lot of community outreach was done during April's Sex Assault Awareness Month, Popp said.

"We anticipated we'd have an uptick," he said. But the rape numbers have dropped from 18 last year to four this year.