Spanovic, 45, was sentenced in 1994 to 20 years' imprisonment for war crimes committed in villages in the Glina area in August 1991, including opening fire on unarmed civilians, torture, pillage and arson.
Despite an international warrant for his arrest, Spanovic lived peacefully in Carlshalton, Surrey, for nearly eight years. His past came to light last October after he received a court warning for theft in a shop in Sutton.
However, a British judge concluded last March that it would be unfair to extradite him for a retrial in Croatia.
A decision to review the case was made after the Supreme Court approved a Croatian government appeal and a local court is now to review the March decision.
At the second extradition hearing, to be presided by judge Timothy Workman, Spanovic's attorneys will allegedly present new evidence and argue that the trial was based on prejudices because the defendant is Serb.
Judge Workman has to decide if the defence witnesses, including a former Croatian judge, will remain anonymous.