A Russian-speaking immigrant accused of practicing dentistry without a license in Oregon claims he was defending himself in the shooting death of a man believed to be a patient.

The Oregonian reports that 80-year-old Viktor Gregorevich Gebauer's attorney said at his murder trial that the man did not have an appointment and threatened Gebauer last year.

Gebauer is accused of shooting 47-year-old Viktor Merezhnikov (muh-REZH-nee-KOFF), who had a crown pulled eight days earlier and had returned seeking relief for his tooth pain.

Prosecutors say the state will present physical evidence that will counter the self-defense claim.

A Multnomah County judge is hearing the trial without a jury. It's expected to last about two weeks.