A covariant spinor representation of iosp(d,2/2) is constructed for the
quantization of the spinning relativistic particle. It is found that, with
appropriately defined wavefunctions, this representation can be identified with
the state space arising from the canonical extended BFV-BRST quantization of
the spinning particle with admissible gauge fixing conditions after a
contraction procedure. For this model, the cohomological determination of
physical states can thus be obtained purely from the representation theory of
the iosp(d,2/2) algebra.Comment: Updated version with references included and covariant form of
equation 1. 23 pages, no figure