Lieutenant Aboubacar Sidiki Diakite, sometimes known as "Toumba," said during his trial that "Everything that happened at the stadium was prepared by President Dadis. It was the children of Kaleah (a military training camp) who descended on the stadium."
In his testimony, Diakite gave details about how the massacre was allegedly planned.
Diakite and Camara are among 11 men standing trial for the massacre on Sept. 28, 2009 in Conakry, when tens of thousands of pro-democracy demonstrators came out to pressure Camara not to stand for election as president of Guinea the following year.
Camara has not yet testified in the trial, which opened on Sept. 28. He has previously denied responsibility for the incident, blaming it on errant soldiers including Diakite.
Camara is expected to give his own version of events when he testifies in coming days.