Discuss signs that professionals in surveillance roles can look for in order to predict and prevent a terrorist attack.

The Open Source Sample Alert provides examples of potential indicators of terrorist activity. Discuss signs that professionals in surveillance roles can look for in order to predict and prevent a terrorist attack. In addition, identify any legal parameters that may limit surveillance abilities. Cite at least one case in which counterterrorism professionals detected terroristic preparation and prevented an attack. Please ensure that your references are peer-reviewed