  It has been recently suggested that the anomalous excess of low-energy
electron-like events observed by the MiniBooNE experiment, could be explained
by the radiative decay of a heavy sterile neutrino nu_h of the mass around 500
MeV with a muonic mixing strength in the range |U_{\mu h}|^2 \simeq (1-4)\times
10^{-3}. If such nu_h exists its admixtures in the decay Ds -> mu+nu would
result in the decay Ds -> mu+nu_h with the branching fraction \simeq
(1.2-5.5)\times 10^{-4}, which is in the experimentally accessible range.
Interestingly, the existence of the Ds -> mu+nu_h decay at this level may also
explain why the currently measured decay rate of Ds -> mu+nu is slightly higher
than the predicted one. This enhances motivation for a sensitive search for
this decay mode and makes it interesting and complementary to neutrino
experiments probing sterile-active neutrino mixing. Considering, as an example
the CLEO-c experiment, we suggest to perform a search for the decay Ds ->
mu+nu_h with the analysis of existing data. The discrepancy between the
measurements and theoretical description of the decay Ds -> tau+nu is also
discussed in brief.
