International prosecutors at The Hague have accused former Ugandan rebel Dominic Ongwen of ordering his men to kill, cook and eat civilians.
He is the first member of the Lord’s Resistance Army (LRA) to appear before the International Criminal Court.
Mr Ongwen has been accused of 70 war crimes and crimes against humanity.
His defence is likely to use his past as a former child soldier and kidnap victim as part of a plea for leniency.
Prosecutors used Thursday’s confirmation-of-charges hearing to try to convince judges there is enough evidence for Mr Ongwen to stand trial.
They said Mr Ongwen had used schoolgirls as sex slaves, conscripted child soldiers and, in at least one instance, ordered his men to kill, cook and eat civilians.
Images shown in the session included a video of shallow graves in the aftermath of an attack.
The prosecution is focusing on attacks on four displaced camps housing civilians driven out by the LRA’s violence.
Mr Ongwen, born in 1975, surrendered in January 2015. He was abducted by the LRA when he was 10 years old and rose to become one of its commanders.
His lawyers are likely to argue he had a traumatised youth as part of a plea for leniency, the BBC’s Anna Holligan at the Hague says.
Dressed in a grey suit, lilac shirt and grey tie, Mr Ongwen rose to say that reading out the charges was a “waste of time”.
He is believed to have been a deputy of LRA commander Joseph Kony, who is still on the run.
Over the next five days, the defence and prosecution will have a chance to outline their arguments.
The judges will then have 60 days to decide whether there is enough evidence to put him on trial.
Who is Dominic Ongwen?
- Said to have been abducted by LRA, aged 10, as he walked to school in northern Uganda
- Rose to become a top commander
- Accused of crimes against humanity, including enslavement
- ICC issued arrest warrant in 2005
- Rumoured to have been killed in the same year
- US offered $5m (£3.3m) reward for information leading to his arrest in 2013
Dominic Ongwen – full profile