Mugambira, 51, appeared before a semi-traditional Gacaca Kigali Court which came to try him in Kibuye, western Rwanda, location of the alleged crimes.
According to the judgement, the businessman was found guilty of having bought rifles and machetes which militiamen used during the genocide and of having had one of his brothers-in-law killed, reported New Times, a daily English private newspaper.
The bench concluded that the defence witnesses had contradicted themselves.
Mugambira was also an influential member of the former presidential party, the National Republican Movement for Democracy and Development (MRND).
The Gacaca courts are not presided by professional magistrates, but by people who are considered of high esteem in the society. These courts, which have already tried more than a million people, are expected to complete their work this year
© Hirondelle News Agency