  We investigate the renormalization of the Gluino-Glue operator, using both
Lattice Perturbation Theory (LPT) and a Gauge Invariant Renormalization Scheme
(GIRS). The latter scheme involves gauge-invariant Green's functions of two
operators at different space-time points, which can be also computed via
numerical simulations. There is no need to fix a gauge and the mixing with
gauge noninvariant operators is inconsequential. We calculate perturbatively
the conversion factor relating GIRS with the Modified Minimal Subtraction
scheme. On the other hand, the Gluino-Glue operator being mixes with several
gauge noninvariant operators which have the same quantum numbers. The
determination of the mixing matrix on the lattice demands the calculation of
2-pt and 3-pt Green's functions with external gluon, gluino and ghost fields
using LPT. We compute at one-loop order the renormalization of the Gluino-Glue
operator and all operator mixing coefficients.
