For this week’s tech segment, we’re looking at surveillance as an aid to terror investigations. How effective are video cameras and other surveillance technologies in catching criminals after the fact (or preventing crime in the first place)? And are some surveillance methods better than others? We talk with two experts.

Grant Fredericks is an analyst with Forensic Video Solutions, a company that he created to analyze video evidence in criminal and civil investigations. And Bruce Schneier is a security technologist and author of ?Beyond Fear: Thinking Sensibly About Security in an Uncertain World.?