  We construct the action of a relativistic spinning particle from a non-linear
realization of a space-time odd vector extension of the Poincar\'e group. For
particular values of the parameters appearing in the lagrangian the model has a
gauge world-line supersymmetry.{As a consequence of this local symmetry there
are BPS solutions in the model preserving 1/5 of the supersymmetries.} A
supersymmetric invariant quantization produces two decoupled 4d Dirac
equations.
