  We analyze the behavior of the energy spectrum of the Klein-Gordon equation
in the presence of a truncated hyperbolic tangent potential. From our analysis
we obtain that, for some values of the potential there is embedding of the
bound states into the negative energy continuum, showing that, in opposition to
the general belief, relativistic scalar particles in one-dimensional short
range potentials can exhibit resonant behavior and not only the Schiff-Snyder
effect.
