AUSTIN -- (KXAN) -- As law enforcement started closing in on the serial bomber, he knew his time was up. A few hours before the showdown on Interstate 35 in Round Rock early Wednesday morning, Austin police say Mark Conditt, 23, made a 25-minute video confessing to the attacks.
Interim Austin Police Chief Brian Manley says the video which he classifies as a "confession" was discovered on Conditt's cellphone after he blew himself up as SWAT officers approached his vehicle. In the video, Conditt talks about what he has done and goes into detail about the seven bombs he constructed, including the one he detonated in his truck as officers approached.
"We’ve told you all along they all have similarities, which they did, as far as specific components but there were also differences between them and on this recording he identifies what those differences were," explains Manley.
While the bomber talks about the destructive tools he used, he never mentions why he committed the acts or why he chose the victims he did.
'He does not at all mention anything about terrorism nor does he mention anything about hate.'
"There was no indication of why these specific addresses in those that were delivered to homes or those that were placed in those communities or those that were mailed. There was no reason given why he selected those individuals," says Manley. Officials are still looking for any connections that might shed light on why he did it.
The lack of a clear motive is something everybody wants to understand, but Manley says "sometimes you can't assign a reason to unrational acts."
Many in Austin were working with the theory that the bomber was targeting people of color since the first three attacks involved two black families and a Hispanic family. Conditt's video didn't shed any light on that either.
"He does not at all mention anything about terrorism nor does he mention anything about hate. But instead, it is the outcry of a challenged young man talking about challenges in his personal life that led him to this point," continues Manley.
In regards to the bombs, Manley says all six devices that Conditt referenced (five that detonated and one package that was still intact) have all been accounted for. In his video, which police say was recorded between 9 p.m. and 11 p.m. Tuesday night, Conditt also described the seventh device — the one he used on himself.
While he did not describe any other bombs, what he said on the video indicated he was willing to take actions in the future. The video does not describe how Conditt learned to make the bombs, Manley told NBC News in a one-on-one interview. "That is something that will come up as well as we look further into his background and who he was prior to becoming the person that bombed our city."
When authorities were able to pinpoint his location, they knew the situation could end badly.
As law enforcement officers staged nearby for about 45 minutes waiting for more resources to arrive, Conditt drove out of the hotel parking lot and made his way southbound on the I-35 frontage road.
Worried he might get on the freeway and cause more damage, Manley says his SWAT officers in unmarked vans took immediate action.
'This can never be called a happy ending, but it's a damn good one...'
"Not knowing where he was going, or what might be next, or if he was armed, there was a decision made to put a stop in that frontage road before he got on I-35 and went somewhere else," Manley explains.
As the officers approached his vehicle and started banging on his window, "a tremendous explosion takes place." For Manley, seeing officers he's known for years going into a situation that was inherently dangerous was "harrowing."
Manley told NBC News police captured the entire confrontation on infrared video from a helicopter.