since the late 1970s, rosemary erickson, a security expert and criminologist has interviewed hundreds of prisoners. surprisingly, thieves say they're worried the least by the very thing that might lead to their capture. >> we asked the robbers what difference cameras make and it was at the bottom of the list of what they look for or what they're concerned about. of the robbers we talked to in prison fewer than 10% were caught from surveillance cameras. >> but a sergeant from the san bernardino sheriff's department believes the true value of the camera is deterrence. >> how many people think about doing something wrong, but don't. kind of like we don't have criminals coming into our stations here at headquarters and saying, you know what? i saw a cop car driving down the road last night or today, so i didn't do the robbery. >>> still, surveillance cameras only provide a record of the crime. >> hurry up! hurry up! >> they may help catch a thief, but they can't protect the person behind the counter. >> you do not want to give the people who work for you such as cashiers and clerks a fals