i had never seen anything like that before. >> reporter: the device as shown in the diagram was a two-inch pipe bomb placed next to a one-liter soda bottle full of gasoline, spray-painted black. a large bolt tied off with a fishing line and acting as a drop weight would fall on a rat trap, causing it to strike a firing pin, kind of like a rube goldberg device. the author also said there was a second secret triggering device as backup. either way the bomb was designed to go off when roberto ayala opened the door of the electrical box. >> it could have been almost anything. >> reporter: now suddenly agent parker saw how they all fit, those confusing bits and pieces he'd been poring over for the past month. >> it was almost like someone had sent us the cover of the puzzle box. >> reporter: so now they matched the bits to the diagram. >> the first thing i looked for was this bolt and there it was. >> the thing that made it exceptionally clear was the fact that the bolt still had some fishing string attached just