The prosecutor at the International Criminal Court (ICC) has dropped all charges against Maxime Mokom, who has been in the court's custody since March last year.
He was accused of several crimes including directing attacks against civilians, murder and rape while being part of the anti-Balaka militant movement in the Central African Republic between 2013 and 2014.
He had denied the charges and said he joined the group for the sake of peace not war.
According to the ICC, the violence by anti-Balaka and rival mainly Muslim Seleka militia in the CAR left thousands dead and more than 100,000 displaced.
ICC prosecutor Karim Khan said that having considered the evidence and "regarding the availability of witnesses, he... concluded that there are no longer any reasonable prospects of conviction at trial even if the charges were confirmed", an ICC statement said.
“We must be unwavering in our commitment to only proceed with cases that present a realistic prospect of conviction," he added.