Even after the identification of the Boston bombing suspects through grainy security-camera images, officials say that blanketing a city in surveillance cameras can create as many problems as it solves.
A network of cameras on city streets and other public spaces increases the chances of capturing a criminal on video but can generate an overwhelming amount of evidence to sift through. The cameras make some people feel more secure, knowing that bad guys are being watched. But privacy advocates and other citizens are uneasy with the idea that Big Brother is monitoring their every public move.
Meanwhile, facial-recognition software and other technologies are making security-camera images more valuable to law enforcement. Now, software can automatically mine surveillance footage for information, such as a specific person's face, and create a giant searchable database.
After last week's bombings at the Boston Marathon, authorities had to sift through a mountain of footage from government surveillance cameras, private security cameras and imagery shot by bystanders on smartphones. It took the FBI only three days to release blurry shots of the two suspects, taken by a department store's cameras.
Compare their quick turnaround with the 2005 London bombings, when it took thousands of investigators weeks to parse the city's CCTV (closed-circuit television) footage after the attacks. The cameras, software and algorithms have come a long way in eight years.