  It is shown that the Kerr-Newman solution, representing charged and rotating
stationary black holes, admits analytic extension at the singularity. This
extension is obtained by using new coordinates, in which the metric tensor
becomes smooth on the singularity ring. On the singularity, the metric is
degenerale - its determinant cancels. The analytic extension can be naturally
chosen so that the region with negative r no longer exists, eliminating by this
the closed timelike curves normally present in the Kerr and Kerr-Newman
solutions. On the extension proposed here the electromagnetic potential is
smooth, being thus able to provide non-singular models of charged spinning
particles. The maximal analytic extension of this solution can be restrained to
a globally hyperbolic region containing the exterior universe, having the same
topology as the Minkowski spacetime. This admits a spacelike foliation in
Cauchy hypersurfaces, on which the information contained in the initial data is
preserved.
