  A method is presented for the reconstruction of both the background and
signal in invariant-mass analyses for two-photon decays. The procedure does not
make use of event mixing techniques and as such is based exclusively on an
event-by-event analysis. Consequently, topological correlations of the event
(e.g. jet structures) are automatically taken into account. By means of the
decay process $\pi^{0} \to \gamma \gamma$ it will be demonstrated how the
procedure allows for determination of the $\pi^{0}$ yield from the observed
decay photons.
