Lt. Abubakar "Toumba" Diakite told Radio France International that he shot Capt. Moussa "Dadis" Camara on Dec. 3 because the junta leader betrayed the democracy of the West African nation.
The former presidential guard commander, who is accused of shooting Camara at point-blank range after an argument, remains at large, and it is unclear how many of the roughly 150 men formerly under his control will stay loyal to him.
Diakite said Camara ordered the Sept. 28 massacre at a pro-democracy rally where a human rights group says 157 people were killed and women were raped in the streets. Camara has in the past blamed Diakite for the massacre.
"I shot him because at a certain point, there was a complete betrayal in my view, a total betrayal of democracy. He (Camara) tried to blame me for the events of Sept. 28," Diakite told RFI in his first broadcast comments since the assassination attempt. "I will not turn myself in because they do not want the truth to be known. They'd prefer to kill me."
Junta officials were not immediately available for comment.
Camara is hospitalized in Morocco and has not spoken publicly since the assassination attempt, leading many to speculate he is incapacitated.
Mineral-rich Guinea has been ruled by strongmen for decades. Camara seized power in a December 2008 coup, hours after the death of longtime dictator Lansana Conte.
Camara promised to quickly hand over power to civilians in elections in which he would not run. But he began dropping hints that he planned to run after all, prompting the massive pro-democracy protest in the capital in September.