The Bomber, the Bomber's Friend, and the Assassin's Daughter

de john pointer found fabian's plight to be particularly heart breaking. The bomber, whoever it might be, came very close to also murdering fabian. As police go after more evidence, someone comes after them, leaving a taunting message out in the field. And now these taunting letters from roberto's killer, almost taking prideful delight in how hed killed the man and almost murdered the boy. Who could it be who would do such a thing? And why then?