rick schwein: so you set a device off. first responders arrive at the scene, and then you set another device that you either detonate remotely or is timed to go off sometime after the first device, you're doing that to kill the people that are responding. that's a different level of evil. bill campbell: the first act is a political statement. the second one is a particularly heinous act that seemed designed to injure those federal and local officials that were there to assist in the evacuation of the emergency medical personnel. joe kennedy: after the sandy springs bombing, we had a good idea of the components that were used in the bombs from centennial olympic park and the two bombs in sandy springs. they were a number of components that were the same-- mechanical timer, nails, steel plates. so these types of similarities, we like to use a term called a “bomber signature.” by that i mean, when you have a serial bomber making multiple bombs, subsequent bombs that he makes will generally incorporate similar design concepts.

rick schwein: he set the thing up to hurt people in a mass way. [crowd clamoring, whistle] mark mckay: we don't know if that person is going to strike again. [blows whistle] let's go! mark mckay: who did this? is it part of a strategy or is it a singular event? we didn't know any of that. [theme music] hello, and welcome to how it really happened. i'm jesse l. martin. in the summer of 1996, all eyes were on atlanta, georgia for the centennial olympics. the southern city put on quite a show for the opening ceremony as muhammad ali lit the olympic flame. but just eight days later, at a celebration in centennial park, a security guard noticed a suspicious backpack under a bench. security and law enforcement moved quickly to evacuate the massive crowd, but time was not on their side. this is how it really happened. [indistinct chatter] it's a weekend night in atlanta. it's hot. the streets are packed. [groovy music] there is entertainment at centennial park. the beating heart at night of the olympics. (singing) something about you driving me crazy the

rick schwein: those early hours are really important because you're trying to preserve forensic evidence, you're trying to identify a good timeline, you're trying to determine who did this. and is it a lone actor or is it a group? are there gonna be follow on attacks? is it part of a strategy or is it a singular event? and we didn't know any of that. [tense music] the samples were taken, given to the guy in charge of the fbi team, and he sent those to washington, dc to be analyzed to identify the explosive. male reporter 1: while the fbi waits for lab results. federal agents are working on a timeline, trying to figure out the 911 call. it was made from a public telephone close to the park, and we were trying to identify where that phone was and who might have been able to see who was making the call. remember, two different things were happening at the same time. in the park, richard jewell had spotted a backpack. and what they don't realize is that there's been a 911 call, warning that there's a bomb in centennial park. that information never gets to them. caller: there is a bomb in cen