  The expected proton and neutrino fluxes from decays of massive metastable
relic particles is calculated using the HERWIG QCD event generator. The
predicted proton spectrum can account for the observed flux of extremely high
energy cosmic rays beyond the Greisen-Zatsepin-Kuzmin cutoff, for a decaying
particle mass of O(10^{12}) GeV. The lifetime required is of O(10^{20}) yr if
such particles constitute all of the dark matter (with a proportionally shorter
lifetime for a smaller contribution). Such values are plausible if the
metastable particles are hadron-like bound states from the hidden sector of
supersymmetry breaking which decay through non-renormalizable interactions. The
expected ratio of the proton to neutrino flux is given as a diagonistic of the
decaying particle model for the forthcoming Pierre Auger project.
