Iraqi forensic teams in the newly liberated city of Tikrit have started exhuming bodies from mass graves believed to contain hundreds of soldiers killed by ISIS last year, a government spokesman said Tuesday.

Kamil Amin, from Iraq’s Human Rights Ministry, said the work started Monday on eight locations inside Tikrit’s complex of presidential palaces.

“We expect to discover more mass graves in different areas,” Amin told The Associated Press. “We expect a huge number of bodies to be unearthed.”