 Authorities do believe crooks acted alone, which made it difficult to prevent. It's like finding a needle in a haystack when you're trying to find a lone wolf because there's less of an evidentiary basis to tip off law enforcement. And authorities still don't have a motive. CBS News security consultant Samantha Vinograd on security concerns going forward. In the aftermath of any high-profile or mass casualty event, there is always a concern by law enforcement and intelligence officials