  We show that existing laboratory experiments have the potential to unveil the
origin of matter by probing leptogenesis in the type-I seesaw model with three
right-handed neutrinos and Majorana masses in the GeV range. The baryon
asymmetry is generated by CP-violating flavour oscillations during the
production of the right-handed neutrinos. In contrast to the case with only two
right-handed neutrinos, no degeneracy in the Majorana masses is required. The
right-handed neutrinos can be found in meson decays at BELLE II and LHCb.
