Abducted by gunmen as a 10-year old boy on his way to school, Dominic Ongwen rose to become one of the most feared commanders in Uganda's brutal Lord's Resistance Army (LRA).
Ongwen, now in his mid-30s, surrendered this week in Central African Republic to US special forces, and may face trial at the International Criminal Court for crimes against humanity and war crimes.
The son of school teachers, he was abducted as a child before being forced into the rebel army and becoming a willing perpetrator of violence.
He then rose swiftly through the LRA's ranks, quickly being singled out for his murderous loyalty and tactical ability and taking command of one of the LRA's four brigades.
Ongwen led quick and lethal raids -- carrying out massacres, rapes, mutilations and abductions -- before disappearing into the bush.
Ongwen's men -- with trademark dreadlocks, mismatched uniforms and AK-47 rifles fitted with bayonets -- carried out thousands of abductions of children. Boys were taken to be soldiers or porters, girls were taken as sex slaves.
They also excelled in punishment raids where they would slice the lips and ears off victims as a grim calling card.
Under the leadership of self-proclaimed prophet Joseph Kony, the LRA is accused of kidnapping tens of thousands of children during its nearly three-decade long insurgency.
Between 2002 and 2003, Ongwen is thought to have directed bloody campaigns in northern Uganda that butchered or abducted thousands. He is also accused of playing a central role in revenge attacks on civilians in the Democratic Republic of Congo.
In recent years, however, he was reportedly sidelined after falling out with Kony over his execution of another commander.
Hailing from the northern Ugandan district of Gulu, Ongwen was known "as much for his volatile nature as his bravery", according to the LRA Crisis Tracker, which monitors the rebels.
Years of psychological trauma are also said to have taken their toll with Ongwen earning a reputation for flying into murderous rages.
Mark Kersten, a London-based academic focusing on international justice, described Ongwen as "both a victim and a perpetrator of international crimes" and said efforts to prosecute him could raise difficult questions.
"When is a victim a perpetrator and a perpetrator a victim? The line is much more murky than we tend to assume," he said.