  We use a theoretical model of the $\gamma ~d \to ~K^+ K^- ~n ~p $ reaction
adapted to the experiment done at LEPS where a peak was observed and associated
to the $\Theta^{+}(1540)$ pentaquark. The study shows that the method used in
the experiment to associate momenta to the undetected proton and neutron,
together with the chosen cuts, necessarily creates an artificial broad peak in
the assumed $K^+ n$ invariant mass in the region of the claimed
$\Theta^{+}(1540)$. It is shown that the LEPS fit to the data, used to make the
claim of the $\Theta^{+}(1540)$, grossly distorts the background. An
alternative fit, assuming a background plus a fluctuation, returns a background
practically equal to the theoretical one and a fluctuation identical to the one
seen in the experimental $K^- p$ spectrum of 2$\sigma$ significance.
