“Just read these devices were sophisticated.”
Yes, that is a key clue here that most are overlooking.
These devices had tilt switches and were apparently not your everyday amateur bombing attempt.
Yes, I think the sophistication of the bombs is a key element, but what does it mean, and does it tie to these specific victims? It takes both effort and knowledge to build a bomb, and you would normally expect a bomber to go after a crowded, target-rich environment, not individual households. A very strange MO.
Tilt switches are not particularly sophisticated.
Right which allowed the package to be placed by the perp easier and not explode on him.