  The MiniBooNE collaboration has reported an excess of $460.5\pm 95.8$
electron-like events ($4.8\sigma$). We propose an explanation of these events
in terms of a sterile neutrino decaying into a photon and a light neutrino. The
sterile neutrino has a mass around 250 MeV and it is produced from kaon decays
in the proton beam target via mixing with the muon or the electron in the range
$10^{-11} \lesssim |U_{\ell 4}|^2 \lesssim 10^{-7}$ ($\ell = e,\mu$). The model
can be tested by considering the time distribution of the events in MiniBooNE
and by looking for single-photon events in running or upcoming neutrino
experiments, in particular by the suite of liquid argon detectors in the
short-baseline neutrino program at Fermilab.
