FBI's Comey: Nothing Agents Could Do Differently

The FBI investigated a security guard for potential terrorist ties after he made inflammatory statements. The investigation involved surveillance and interviews but was closed after 10 months due to lack of evidence. The case resurfaced when the guard was indirectly linked to a suicide bomber, but no significant ties were found. The FBI reflects on the challenges of such investigations and the need for continuous improvement.

How did the investigation connect the security guard to the suicide bomber for Al Nusra?

What challenges does the FBI face in their investigations according to the text?