Bulgaria's former interior chief secretary blamed settling scores between business rivals for the murder of former Primer Minister Andrey Lukanov.

Tsvyatko Tsvetkov, who led the investigation in the first days after the murder, told Darik News all possible versions have been probed, not without the help of European police organizations.

A day earlier a supreme court fully and definitively cleared the five defendants in the trial for the murder of Lukanov. The verdict, which upheld an earlier ruling of a lower court, is final and is not subject to appeal.

Two Ukrainians - Alexander Russov and Alexey Kichatov, Bulgarian construction entrepreneur Angel Vassilev, his nephew Georgi Georgiev and his driver Yuri Lenev were sentenced to life imprisonment at the end of November 2003.

The life sentences of the defendants were reversed at the beginning of June last year by Sofia Court of Appeals.

More than ten years after Andrey Lukanov's killing, Bulgaria still has not tracked down the murderers.

Bulgaria's former Prime Minister Andrey Lukanov was killed on 2 October 1996 in front of his Sofia home. He was a member of the Moscow-trained Bulgarian communist elite, served as government head from the Socialist Party from 1989 to 1990. At the time of the murder Lukanov was a lawmaker for his party.

His activities in the turbulent years of Bulgaria's transition from communist regime to democracy have been subject to heated controversy during the years, but it is his emblematic role in Bulgarian politics that can never be denied.