For me it was Tori Stafford. We lived just outside of town at the time and the day the alert went out I was in town running errands and the command post was being set up. Cops cars *everywhere*, helicopters overhead nearly 24/7 and several times they came down very low over our place. Before they found her I found out WAY more than I could ever post publicly (although I hadn't registered here yet, I was lurking) and it sickened me. I know everyone wants to give it a nice, neat, medical label but I honestly believe there are just truly evil people among us.
ETA: One of the most heartbreaking things about the Tori Stafford case? The duplex where Rafferty's GF lives, is one I drive by *all* the time to go to my usual places to run errands. Tori loved butterflies and purple was her favorite color (another one to add to the Purple Girls) so someone had a ton of purple butterfly stickers made up. People had them everywhere, their cars, windows on their homes, etc. On the screen door of the duplex right next door to the killer's GF, was a Purple Butterfly Tori sticker. I saw that one day when I drove by and saw the police tape around the building, and just wept all over again.