Stig Sandström is just an alias for the real Sovjet-spy and renegade Stig Bergling, who defected in 1987 and successfully ran from the secret service watch.
Evgeniy Lazarev played Tjivartsjev in this, Tribunal (1995) and Hamilton (1998), while Hamilton was played by three different actors: Peter Haber, Stefan Sauk and Peter Stormare.