Core excitation triggers nuclear dynamics on the femtosecond time scale. A multiparametric electron/ion coincidence approach has been used to disentangle complex decay processes occurring at short (molecular) or long (atomic) time scales. Methyl chloride has been excited by scanning along the dissociative Cl2p-->sigma* resonance. The detailed chronology of the competing decay processes, leading to either the rearrangement product HCl(+), or an ultrafast dissociation leading to Cl(+), has been investigated. The observed Auger-Doppler shift has been analyzed for various orientations of the electron and fragment ion.