  We present the first systematic study of the gravitational collapse of
rotating and magnetised neutron stars to charged and rotating (Kerr-Newman)
black holes. In particular, we consider the collapse of magnetised and rotating
neutron stars assuming that no pair-creation takes place and that the charge
density in the magnetosphere is so low that the stellar exterior can be
described as an electrovacuum. Under these assumptions, which are rather
reasonable for a pulsar that has crossed the 'death line', we show that when
the star is rotating, it acquires a net initial electrical charge, which is
then trapped inside the apparent horizon of the newly formed back hole. We
analyse a number of different quantities to validate that the black hole
produced is indeed a Kerr-Newman one and show that, in the absence of rotation
or magnetic field, the end result of the collapse is a Schwarzschild or Kerr
black hole, respectively.
