The exile / Allan Folsom.

Enhanced descriptions from Syndetics:

Night in the California desert: John Barron---the youngest cop on the LAPD's feared 5-2 squad---will get a baptism of blood and fire on a night he will never forget.
Panic on the streets of LA: An international hit man no one can stop---not the governments he threatens, not the prisons that try to hold him, not LA's bloodiest rogue cops.
Rebecca Barron, John's ravishingly beautiful sister: A night of traumatic terror has left her tragically mute. Now, trapped in a web of global intrigue---and pursued by the same sinister hit man menacing institutions of power worldwide---she will find the shocking violence that robbed her of her speech was only the beginning of a far darker odyssey.
A world-famous baroness---as sensuous as she is singularly cruel---will stop at nothing to fulfill her own maniacal dream, one destined to topple governments and dethrone dynasties, catapulting her to the pinnacle of global power . . . while the world holds its breath and waits.