Milan, 6 May 2009. Pasqualina Labarbuta stops on a bench for her lunch break. A few minutes later, a stab wound to the heart kills her. No robbery, no motive, just a man with a white jacket fleeing. Sixteen years later, the mystery remains: a single perfect slash, a Sardinian knife abandoned in the grass, a trace of DNA that leads to no one. Who hit Pasqualina? And why her, that day? The complete analysis by investigative journalist Alessandro Politi is online on social media and IlGiornale channels.