Violent crime at Baltimore County shopping centers that have installed security cameras have fallen by nearly a third since 2006 — about twice the countywide rate of decline, according to a police study.

County Councilman Kevin Kamenetz, who introduced legislation in 2005 to require video cameras at shopping centers with 15 stores or more, discussed the report's findings Monday outside the Shops at Kenilworth in Towson.

"I don't want to suggest that cameras alone are responsible for the drop," said Kamenetz, who is running for the Democratic nomination for county executive. But he said they are part of the reason for the 31 percent decline at shopping centers with cameras. He called the improvement a "testament to the continued efforts of Baltimore County's police, private security guards and the use of technology."

Police Chief Jim Johnson, who did not attend Kamenetz's news conference, agreed that the law requiring cameras "contributed to the significant decreases in crime over the past three years."

"In addition," he said in a statement, "it has been a very valuable asset in obtaining evidence that has been used by our officers and detectives in solving crimes, and arresting those committing them."

The report, which compares the three years before the installation of the cameras in 2006 with the three years since, takes into account incidents at 42 shopping centers.

Aggravated assaults and robbery of individuals each dropped more than 37 percent. The number of homicides dropped from three to one, and the number of rapes fell from one to none.

Kamenetz introduced the legislation weeks after the February 2005 killing of a St. Paul's School dean during a robbery attempt on the top deck of the Towson Town Center parking garage. The legislation was adopted the following month, requiring that shopping centers install cameras by September 2006. Shopping center owners had the option of applying to the county for money to help pay for the cameras.

arthur.hirsch@baltsun.com