In the old days, detectives at a crime scene would scour the area for witnesses and physical evidence.Now they also look for something else, and usually they find it: security cameras.

The growing number of cameras installed to enhance the safety of public buildings and private homes is also providing police with invaluable evidence.
"The technology has definitely evolved," said Lt. Frank Vanore, a Philadelphia Police Department spokesman. "It's becoming more important, and we're getting better at working with it."

Modern homicide detectives don't just look down, searching the street for shell casings and blood spatters - they look up, for cameras that might have captured the crime.
Experts who study the use of security cameras in American society say that at this point, criminals ought to know better. Cameras are everywhere.

People are routinely recorded when they extract money from an ATM, drive through a toll booth, stroll past a business, or even take a young lady into a hotel room - as discovered by Joran van der Sloot, charged with murdering 21-year-old Stephany Flores in Peru and long suspected in the disappearance of American student Natalee Holloway in Aruba.
Across the United States, colleges and transportation agencies - in Philadelphia, including SEPTA and the University of Pennsylvania - typically allow police to tap into their network of cameras.

Society has drawn the line at putting cameras in store dressing rooms and public bathrooms, he said, but most other areas are open to video recording by police agencies, businesses, or citizens.

"Most of the time, we no longer think about it," he said. "We've become so accustomed to being a video society."

A camera captured the entrance of his Lincoln MKS, followed by a Toyota. Minutes later, surveillance video showed a man and woman approaching Caballero, who had parked. A few minutes after that, a third camera recorded the Lincoln pulling out, followed by the Toyota.

Those shots were the first of nearly a dozen taken over four hours that helped authorities track the suspects' movements. One camera showed Arno withdrawing $300 with Caballero's ATM card.

In Camden, surveillance cameras helped authorities make arrests in two recent homicides.

"When video is available, it can be enormously helpful," said Jason Laughlin, a spokesman for the Camden County Prosecutor's Office.

Currently, the Police Department is able to view footage from more than 600 cameras throughout the city, including lenses around City Hall.

"It's not like years ago when we would just bring a VHS tape back to headquarters," Vanore said. "You have to look at these videos for hours, just to find that one second where someone's going by."