I feel that "The Raging Bomber" and "Mad Bombings" are similar enough in name and theme to trigger an echo ("raging" and "mad" are synonyms, both applied to a serial bombing spree). Additionally, for character development reasons I've had him focus on cases that are primarily kidnappings rather than the darker stuff like serial killers (that comes later), but since he's deeper into detective work now and interested by Naomi's work with the crime lab, it's the first time he's heard about a serial bomber in the context of something he could potentially work on at some point (and did, according to his preincarnation).