Indeed, who knows for sure.It appears that Rasmussen has flushed Hesjedal out. Though, whether honestly or conveniently, the admission only applies to events outside the statute of limitation.
http://road.cc/content/news/98037-2012-giro-champion-ryder-hesjedal-admits-doping
That's the only time that Rasmussen and Hesjedal were together. I think we have to assume that RH fessed up to USADA and Garmin (JV) when the Rasmussen book was first mooted. RH must have known he was liable to be fingered. Not exactly open and honest if that's the case.
Whether that taints his Giro win is for individuals to decide.