  We present a Lagrangian formulation for 4d integer-spin relativistic fields
in the 5d space spanned by two conjugate Weyl spinors and a Lorentz-invariant
proper-time coordinate. We construct a manifestly Poincare-invariant free
classical action, find a general solution to equations of motion and a
corresponding positive-definite inner product. Our formulation displays a
separation of variables: equations of motion represent ODE in a proper time
only, while spinor coordinates parameterize the Cauchy hypersurface. We also
find momentum eigenstates solutions for massless arbitrary integer-spin fields
and a massive scalar field.
