diagram. it would have been hanging from that string as a weight. correct. right. so that was very clear that that bolt was in fact part of our device that was described in the letters. reporter: and there were fragments of a plastic soda bottle, black paint still clinging to it again just like the diagram. there was a spring that was similar to a rat trap spring. there was gasoline on the victim s clothing. and then we recovered pieces of a nine volt battery that we were able to determine had no business being in that panel. reporter: so if you found the writer of those letters you had found your killer. that was our opinion. yes. reporter: along with the diagram was a second letter in which the bomber repeated his earlier claim that he was a reluctant assassin. after a career of killing, he wrote, i want to save a life wrote, i want to save a life
underneath the head of the bolt, which is how it was depicted in the diagram. it would have been hanging from that string as a weight. correct. right. so that was very clear that that bolt was in fact part of our device that was described in the letters. reporter: and there were fragments of a plastic soda bottle, black paint still clinging to them, again just like the diagram. there was a spring that was similar to a rat trap spring. there was gasoline on the victim s clothing. and then we recovered pieces of a 9 volt battery that we were able to determine had no business being in that panel. reporter: so if you found the writer of those letters, you had found your killer. that was our opinion. yes. reporter: along with the diagram was a second letter in which the bomber repeated his earlier claim that he was a reluctant assassin. after a career of killing, he wrote, i want to save a life before i take my life. the bomber repeated his warning.
almost as someone sent us a cover to the box. they matched the bits to the diagr diagram. the first thing i looked for was the bolt. there it was. the thing that made it exceptionally clear was the fact the bolt still had some fishing string attached just underneath the head of the bolt which is how it was depicted in the diagram. so it would have been hanging from that string? correct. as a weight? right. and so that was very clear that that bolt was, in fact, part of our device that was described in the letters. and there were fragments of a plastic soda bottle. black paint still clinging to them. again, just like the diagram. there was a spring that was similar to a rat trap spring. there was gasoline on the victim s clothing. and then we recovered pieces of a 9 volt battery that we were able to determine that had no business being in that panel. so if you found the writer of those letters, you had found your killer. that was our opinion, yes.
rick leventhal with more. hi, rick. we ve seen the criminal complaint. in it, authorities say the suspect akayed ullah admitted to building the pipe bomb and detonating it intentionally. law enforcement sources said he gathered the pieces from job sites where he was an electrician. he used christmas tree lights, wires and a 9 volt battery for detonation and zip ties to attach it to his body. the complaint says that ullah s radicalization began three years ago in 2014 when he used pro isis materials online. that was three years after he came to the united states. benefit of the family immigrant visa program. authorities say he began researching how to build and improvise explosive devices online about a year ago. we re learning that yesterday morning he posted a message on