MINNEAPOLIS (AP) -- A trial is set to begin for a Minneapolis police officer who fatally shot an unarmed Australian woman after she called 911 to report a possible sexual assault happening in the alley behind her home.

Thirty-three-year-old Mohamed Noor, who was fired after the shooting, is charged with murder and manslaughter in the July 2017 death of Justine Ruszczyk Damond.

Experts say the case will be challenging for both prosecutors and the defense.

Prosecutors must prove Noor acted unreasonably when he shot Damond. The defense plans to argue that Noor used reasonable force and acted in self-defense.

Noor refused to speak to investigators about what happened. His attorneys haven't said whether he'll testify.

The trial is expected to last weeks.