Milenkovic fled the country after the assassination, which was carried out on March 12, 2003, and was arrested near Serbia and Montenegro's Consulate General in Thessaloniki on July 16, 2004.
A special Serbian court dealing with cases of organised crime and corruption also charged Milenkovic with participating in six murders and three abductions that were carried out by members of the notorious Zemun Clan, of which he was a member.
Milenkovic's testimony is expected to shed new light on the assassination of Djinjdic at a trial that started in December 2003.
The chief suspect in the case is former special police chief Milorad Lukovic aka Legija, who turned himself in last May after a year-long police search. He denied all the charges.