Dmitry Kaloev, 29, is the son of well-known activist and journalist Fatima Margieva. He was arrested in South Ossetia in March 2010 after his friend, Vyacheslav Bichenov, died of a drug overdose. He has been held in detention since then.
Investigators insisted in the trial that concluded on March 9 that Kaloev and Bichenov had used heroin and Kaloev is responsible for his friend's death.
Kaloev pleaded not guilty and said he never used drugs.
Margieva told RFE/RL the case against her son is politically motivated and connected to her professional activities. Margieva has written several articles critical of the de facto government in South Ossetia.
Last year, Margieva was found guilty of possessing illegal weapons, ammuniton, and explosives and given a two-year suspended prison sentence.
Margieva told RFE/RL her son has spent one year in jail already and is due to be released at the end of June.