BERLIN (AP) — An 18-year-old man on trial over the death of German-Turkish student Tugce Albayrak said Friday that he regretted his actions.

The defendant, identified only as Sanel M., told a regional court in Darmstadt on the opening day of his trial that he slapped Albayrak in the face before she fell to the ground. The 23-year-old student died two weeks after the Nov. 15 altercation at a fast food restaurant in the city of Offenbach, prompting outrage in Germany and Turkey.

"I'm eternally sorry for what I did," German news agency dpa quoted the defendant as saying in court. "I never expected her to die."

Witnesses said Albayrak had earlier come to the aid of two girls who were being harassed by the defendant and another man. The girls, aged 13 and 14, were scheduled to testify at a closed-doors session Friday afternoon.

M., who prosecutors say had previous run-ins with the law, is on trial charged with bodily harm resulting in death. If convicted, he could face a minimum sentence of six months or three years, depending on whether he is sentenced as a juvenile or as an adult.

A verdict is expected in June.

After her death, German President Joachim Gauck praised Albayrak as a hero and a role model for trying to help others.