Every day, millions of packages are delivered through the mail in the United States but for 19 days, a bomber held the city of Austin, Texas, hostage. He had residents terrified due to the unpredictable nature of his attacks.

By the time police had managed to catch up with the 23 year old suspect Mark Anthony Conditt, 6 bombs had been detonated, killing two people and injuring 5 more. These attacks were carried out just over a year ago in March, 2018 but for the first time ABC News’ “Nightline” takes you inside the investigation that brought down one of the most prolific bombers in American history.

We hear from the law enforcement officers who were on the frontline, from the Austin police, the bomb squads, FBI and ATF agents, as they reveal the never before seen details on how they managed to capture him.