SEATTLE -

The attorney representing the man accused of killing one student and wounding two others at a Seattle university says she is planning to pursue an insanity defense for her client.

Aaron Rey Ybarra pleaded not guilty to premeditated first-degree murder and other charges on Monday morning in King County Superior Court.

If convicted of all charges, Ybarra could face a sentence of up to 86 years in prison. King County Prosecutor Dan Satterberg has said, however, he will seek an exceptional sentence that could put the 26-year-old in prison for life.

Officials say Ybarra fatally shot a 19-year-old Seattle Pacific University student and wounded two others. He was stopped from shooting more people by a student building monitor who pepper-sprayed and tackled him as he reloaded his shotgun.