Sofia's Court of Appeals will hold on Monday a new session on the assassination case of Bulgarian ex-Premier Andrey Lukanov.
Five people, including two Ukrainians, are appealing against their life sentences.
Two Ukrainians, Bulgarian entrepreneur Angel Vassilev and his driver Yuri Lenev, as well as Georgi Georgiev were sentenced to life imprisonment at the end of November 2003.
One of the two Ukrainian suspects - Alexander Russov - was pointed by prosecutors as the perpetrator of the 1996 assault against Lukanov, one of the leading figures in the country's former communist regime.
Building contractor Angel Vassilev was named by the prosecution as the mastermind of the murder, allegedly driven by economic motives. The others were pointed as accomplices in the crime.