AUDIE CORNISH, HOST:
FBI Director Christopher Wray said it was a fingerprint and DNA that helped lead them to the suspect Cesar Sayoc. We're going to speak now with Ari C. Shapira. He's a special agent in charge of the Miami Field Division for the Bureau of Alcohol, Tobacco, Firearms and Explosives. And he joins us now to talk about how an investigation like this unfolds. Welcome to the program.
ARI C SHAPIRA: Thanks for having me.
CORNISH: So we heard earlier that the FBI Director Christopher Wray saying that these - confirmed that these packages were not hoax devices. So how can we tell how dangerous they were?
SHAPIRA: Well, I can't really specifically comment on this investigation obviously. And I think that time is going to really lay out motivations and all of the forensic evidence that's going to be necessary to reach a successful resolution and completion of the investigation.
CORNISH: Now, since you were at one point on a Terrorist Explosive Device Analytical team - right? - you understand sort of what investigators are looking for. So how - what are the kinds of things they look for, especially when packages are found in different states?
SHAPIRA: Well, what generally happens is there's a post-blast investigation. And often in a post-blast investigation, you're left with debris. That requires a reconstitution - a reconstruction of a device that went boom. Fortunately, in this scenario, there were 13 devices that did not go boom. So there's a ton of evidentiary opportunity for forensic exploitation, which the director of the FBI has indicated led to the arrest of this individual.
CORNISH: Meaning they can take it apart and try and trace the materials?
SHAPIRA: Exactly. And there are a whole litany of techniques that are used. And it's not simply just the forensic exploitation. Obviously we live in a world of social media, and everybody has an online fingerprint. There's increased surveillance in a post-9/11 world. And sadly we're getting more and more experienced in this over time, which makes us better at quickly bringing these cases to a successful resolution.
CORNISH: You talked about social media. People are paying attention to what they are perceiving as his political persuasion. So how does a detail like that get weighed in this kind of investigation?
SHAPIRA: Well, it's difficult. Obviously there is a constant weighing of individual's civil liberties, which we all cherish. It's part of my mandate to respect and support the constitutional liberties of all. Domestic terrorism, which we've seen in the United States - you know, political terrorism generally has an element of either a criminal act that's used to intimidate civilian populations or influence government leaders or impact governmental operations. And we often see that in the words that are spoken online. Now, people do enjoy that freedom to voice their opinions. Attorneys are generally the best deciders when that steps over the line. The courts are generally the best deciders when that steps over the line.
CORNISH: We heard the FBI director caution that there could be more packages out there. How do investigators deal with that possibility?
SHAPIRA: Well, again, I'm not going to speak to the specifics here. But increased surveillance would be certainly one technique and using the vehicle that we already know that these devices were sent - certainly the mail system - and for those of us who might be targets, increased vigilance.
CORNISH: Have you seen anything like this before in your experience?
SHAPIRA: No, I haven't. This - actually the fact that none of these devices activated, I have not, no.
CORNISH: That's ATF Special Agent in Charge Ari C. Shapira on the line from Miami. Thank you so much.
SHAPIRA: Thank you, Audie. Transcript provided by NPR, Copyright NPR.