SIKASSO, Mali (Reuters) - A Malian court began a trial of former coup leader General Amadou Sanogo on Wednesday on charges of “complicity in kidnapping and assassination,” three and a half years after his junta was accused of killing 21 soldiers.

Sanogo led a coup in March 2012 that deposed former President Amadou Toumani Toure and plunged Mali into chaos, enabling Tuareg rebels and Islamist militants to take over the north. He was arrested in December 2013.

Authorities in the same month found a mass grave believed to contain the bodies of missing soldiers. He is accused alongside 17 others of involvement in their deaths and faces a possible death penalty.

Sanogo entered the court in the southern city of Sikasso wearing a suit and tie. A crowd of supporters cheered him on while family members sat solemnly wearing white. The trial was adjourned until Friday before he had the opportunity to plead.

Rights groups have applauded the trial as a rare case of justice involving a high profile figure in a region where abuses by military strongmen often go unpunished.

“The trial of General Sanogo and his co-defendants represents clear progress in tackling the culture of impunity in Mali,” Corinne Dufka, associate Africa director at Human Rights Watch, said in a statement.

“For far too long, men like Sanogo were considered untouchable and above the rule of law.”

Sanogo’s coup allowed Tuareg separatists and al Qaeda-linked fighters to occupy Mali’s vast north until they were scattered during a French-led intervention in January.

A peace deal signed with the separatists in mid-2015 has failed to end violence and factional infighting that continues to threaten the stability of Mali and the wider West Africa region.