  We have studied the scalar field as well as the fermonic field perturbations
in the background of the massless BTZ black holes. Comparing with the
perturbation results in the generic nonrotating BTZ black hole background, we
found that the massless BTZ hole contains only normal modes in the
perturbations. We argued that this special property reflects that the massless
BTZ black hole is a different phase from that of the generic nonrotating BTZ
hole.
