Two weeks ago the same court sentenced Mandic with the right to appeal to nine years in jail for abusing his official position and powers and for embezzlement of Privredna Bank funds in East Sarajevo.
The new indictment charges Mandic of organising an attack on the then police school in Sarajevo at the start of the war in Bosnia and of controlling the events in prison outside Sarajevo and Foca where non-Serb prisoners were abused and killed.
The prosecution said in the opening statement that more than 50 witnesses would take the stand and confirm Mandic's responsibility.
Mandic's defence attorney said his client was not responsible for the abuses that took place in the prisons.
Mandic had earlier pleaded not guilty to all counts of the indictment.