The trial of Malian jihadist Al Hassan Ag Abdoul-Aziz is expected to begin at the International Criminal Court in The Hague on Tuesday.
Mr Abdoul-Aziz is accused of war crimes and crimes against humanity in Mali.
He headed the Islamic police in Timbuktu eight years ago when it was under the control of Islamist militant groups Ansar Eddine and al-Qaeda in the Islamic Maghreb.
Mr Abdoul-Aziz, 43, is only the second person to face trial at the International Criminal Court over his actions during the devastating war in Mali nearly a decade ago.
As the head of Islamic police, he is accused of involvement in torture, rape and sexual slavery.
Many girls and women were allegedly forced to marry militants who had established control over the ancient city of Timbuktu.
He is also accused of ordering the destruction of historic monuments and buildings dedicated to Islam.
Mr Abdoul-Aziz was handed over to the ICC in 2018 by the Malian authorities.
The only other man ever tried over his involvement in the conflict in Mali is Ahmad al-Faqi al-Mahdi, who admitted to destroying nine mausoleums and a mosque in Timbuktu.
He was jailed for nine years in 2016.