Thomas Plamberger faces manslaughter charges for the death of his girlfriend, Kerstin Gurtner, during a winter ascent of Austria's Großglockner mountain earlier this year.Prosecutors allege Plamberger exhibited gross negligence by starting too late and delaying his call for help until after dark, leading to Gurtner's death.Plamberger denies the charges, claiming the incident was a tragic accident, but he is held responsible for planning and equipment as the more experienced climber.