The FBI has arrested around 440 rioters that participated in the Siege of the White House (NBC News). The event resulted in 140 injuries to law enforcement officers. Several undetonated explosive devices were found in the vicinity of the DNC and RNC headquarters. The perpetrators have not been caught and the FBI is asking for help from the public on identifying them (Yahoo News).
Wouldn’t it be weird if the ones who encouraged the demonstrators were working with the guys that made sure the National Guard no showed? Great way to get people into a situation where they can be identified. More importantly they can be investigated to identify those they associate with and so on.
A similar strategy might be to have your own guy start a terrorist group. Training camps where extremists come to be educated in the ways of jihad, and also identified and tracked. These guys are notoriously difficult to find.
Sometimes the intel is more valuable than arresting the individuals. It may be more advantageous to let them go back into their natural environment and monitor them to gain identities of more people they might consider dangerous.