On a drizzly Wednesday in March, Swiss police arrested a man standing alone at a Bitcoin A.T.M. near Geneva Airport, ending a nearly year-long manhunt. Hours earlier, the 61-year-old had reportedly bought a one-way ticket to Dubai. All that was left was to convert a supposedly large crypto-currency ransom he’d wrangled into cash. Then, presumably, he would vanish—leaving behind what federal authorities describe as a campaign of violence that had quietly terrorized Geneva.

Four attempted bombings are an anomaly in one of the world’s safest countries. Geneva, in particular, is home to the rich and discreet—where old-money families run private banks and travel to Alpine chalets on weekends. In a place of closed doors and quiet fortunes, violence such as this unnerves the public and punctures the illusion of control.