  A model independent method to search for particles of unknown masses in
events with missing energy is presented. The only assumption is the topology of
the decay chain. The method is tested in events with top pairs decaying
leptonically with the presence of two neutrinos in the final state. Possible
applications are searches for a heavy resonance decaying to top pairs as well
as next generation heavy quarks. Similar topologies are predicted by
supersymmetric models with R-parity conservation resulting in final states with
two invisible neutralinos.
