BERLIN — An Iraqi man accused of being an Islamic State terrorist has gone on trial in a high court in Frankfurt accused of genocide, human trafficking, and the torture and murder of a 5-year-old Yazidi girl he had held as a slave in Falluja, Iraq.

Opening statements in the trial of the defendant identified by his first name and last initial in accordance with German privacy rules, Taha Al-J., came a year after his German-born wife went on trial over the death of the same girl.

His trial is believed to be the first in the world that carries the charge of genocide in relation to the Yazidis.

“This trial is remarkable in many ways,” Alexandra Lily Kather, an international law expert, said in a telephone interview. “This is the first case going on trial in the world including genocide among the charges with respect to crimes committed against the Yazidi.” Ms. Kather co-authored a report on the trial’s significance for Just Security, a legal blog.