Transcript for One year since Austin package bombings
We move now to the story and Austin, Texas it was one year ago a series. Of bombings there packages were left killing two people seriously injuring several others. Tonight ABC's Nightline has an exclusive look at what happened. And how law enforcement was able to find the suspect ABC's Josh Rowan is here with more just what can you tell us I know you guys to spend considerable time. Investigating this piece in you have that laid out Forrest never Nightline but but what can you tell us. Well Byron one year ago today. What had been one package bomb and Austin. Turned into three and with that federal law enforcement local law enforcement realize that this was a serial bomber. It would go on to become. The most prolific series of bombings. Ever in modern American history and it took. Unprecedented. Resources and manpower from local and state law enforcement but also from Washington. People didn't realize because law enforcement. Didn't want to advertise it. But there was tremendous fear on the part of the government police the FBI the ATF and they poured. Millions of dollars millions of dollars in resources. Vehicles equipment and hundreds. Of agents into Austin, Texas to to solve this and what ended up happening from. March 2 2018. Which was the first bombing. So march 12 which was the second and third. And then finally to the culmination of this which was on March 21 along that same interstate 35 in Texas. It was just an incredible. Series of events and really just a remarkable. Investigation. I know you're Europe are reporting on its shows the connective tissue through these agencies now historically there's always been this notion that. Many law enforcement AG's he's have a difficult time. Working together but in this case they worked particularly well together in close how do you explain. I don't really know how to explain why this one worked for the cooperate in terms of cooperation and others don't we saw that the terrible Las Vegas shooting. It in October of 2017. And we saw there was a difficult relationship between local and federal law enforcement. But the truth is what we did find on the ground here. Is that in Austin the feds and the locals and the state all the agencies at every level work together and we found out in our reporting. That the US attorney had actually. The gun some sort of coordination process long before. These bombing started. But he had started bringing in all the various agencies to just get to know each other to start building those relationships and the cooperation and perhaps. It was just that good will that had been built up that led to this effective. Investigation because truthfully. It would be hard to to see this whole thing being solved as quickly as it was but for the cooperation among the agencies. Just let's talk transparency. For a moment this is original reporting by senior team here and ABC news. Take the view or help us understand some of the efforts they went into two compiling this this this complicated report. Visit there's a lot that goes into the sausage making of a news program but. What happens here was the the bombings series came to conclusion. With the the killing of mark conned that the bomber who set off the final device alongside the interstate that night that early morning. March when he first. And after that there was a lot of work an investigation or work on our partisan news organization. To go through and and learn what happened then learn about Condit and find out if there were any accomplices. All the kinds of things you do in in a story like that. From that part not point. Myself and other members of our team. Spent a lot of time working with the agencies the Austin police. The ATF the FBI and our partner television station in Austin cave you. And we try to to get. These organizations. To work with us to tell this story. We saw going in. That this was not the average investigation as you said in terms of the cooperation but also we had. The most prolific bomber in modern American history we had Boston which is. Has become an iconic town iconic city it's the eleventh largest city in the country. These bombings occurred during SXSW. Last year were right now in the middle of SXSW. Again the annual. Tech and music festival. So our goal was to build up the relationships and the trust so that everybody would want to work with us to tell the story of what really happened then pull back the curtain and maybe reveal. Some of the secrets of how law enforcement does its work. They might not necessarily have otherwise want that it but after of course of the months of working this out and learning about this investigation and then importantly. The federal investigation. And the state investigation being closed by prosecutors. The APD Austin police the FBI the ATF. Really graciously brought us and and and gave us access. Not only to their leadership but that people actually were responsible for the critical points in this and then additionally. You know Home Depot which played a critical role they also help tell their story. Josh Margolis thank you so.
This transcript has been automatically generated and may not be 100% accurate.