  In the context of studying black hole singularities by the AdS/CFT
correspondence, we study the BTZ black hole by a scalar field propagating on it
and the corresponding two-point Green functions. We explore how positions
inside the horizon are encoded in the boundary theory. The main idea is to
relate two different semi-classical approximations of the Green function and
see how this indicates the bulk-boundary correspondence. From a key observation
of Festucia and Liu, which is a frequency-geodesic identification, we deduce a
geodesic approximation from the saddle point approximation. As an application,
we find saddles of the Green function and hence their corresponding geodesics.
The conclusion is that some of these geodesics do go inside the horizon. This
gives the possibility of resolving the singularity from the boundary theory.
