  Large-amplitude, high-luminosity soft X-ray flares were detected by the ROSAT
All-Sky Survey in several galaxies with no evidence of Seyfert activity in
their ground-based optical spectra. These flares had the properties predicted
for a tidal disruption of a star by a central supermassive black hole. We
report Chandra observations of three of these galaxies taken a decade after
their flares that reveal weak nuclear X-ray sources that are from 240 to 6000
times fainter than their luminosities at peak, supporting the theory that these
were special events and not ongoing active galactic nucleus (AGN) variability.
The decline of RX J1624.9+7554 by a factor of 6000 is consistent with the
(t-t_D)^(-5/3) decay predicted for the fall-back phase of a tidal disruption
event, but only if ROSAT was lucky enough to catch the event exactly at its
peak in 1990 October. RX J1242.6-1119A has declined by a factor of 240, also
consistent with (t-t_D)^(-5/3). In the H II galaxy NGC 5905 we find only
resolved, soft X-ray emission that is undoubtedly associated with starburst
activity. When accounting for the starburst component, the ROSAT observations
of NGC 5905, as well as the Chandra upper limit on its nuclear flux, are
consistent with a (t-t_D)^(-5/3) decay by at least a factor of 1000. Although
we found weak Seyfert~2 emission lines in Hubble Space Telescope spectra of NGC
5905, indicating that a low-luminosity AGN was present prior to the X-ray
flare, we favor a tidal disruption explanation for the flare itself.
