Naser Oric, the Muslim defender of Srebrenica against separatist Serb forces during Bosnia's 1992-95 war, was extradited to Bosnia from Switzerland on Friday, the Swiss Federal Office of Justice said.
"Accompanied by a Swiss police escort, he arrived in Sarajevo in the afternoon where he was returned to local authorities," the FOJ said in an emailed statement.
Oric was arrested by Swiss police last week on a warrant issued in 2014 by Serbia accusing him of war crimes against Bosnian Serbs in the Srebrenica region during the Bosnian war.
The Swiss government said on Thursday it would extradite Oric to Bosnia. However, Serbia had also sought his extradition, and the decision to send him to Bosnia has angered some Serb and Bosnian Serb politicians.
The row has threatened to overshadow next month's 20th anniversary commemoration of the Srebrenica massacre.
More than 8,000 Muslim men and boys were executed in the days that followed the town's fall to Bosnian Serb forces near the end of the war, events that have been pieced together in hours of testimony and investigation at a United Nations court in The Hague.
However, that account continues to be questioned by Serbs who dispute the death toll and say the whole event has become politicized.