  Based on three years of Fermi Large Area Telescope (LAT) gamma-ray data of
the Virgo cluster, evidence for an extended emission associated with dark
matter pair annihilation in the b b-bar channel has been reported by Han et al.
[1]. After an in depth spatial and temporal analysis, we argue that the
tentative evidence for a gamma-ray excess from the Virgo cluster is mainly due
to the appearance of a population of previously unresolved gamma-ray point
sources in the region of interest. These point sources are not part of the LAT
second source catalogue (2FGL), but are found to be above the standard
detection significance threshold when three or more years of LAT data is
included.
