FARGO, N.D. — A judge has refused to accept a guilty plea from a man accused of killing his ex-girlfriend and another man at a north Fargo apartment last month.

Thirty-five-year-old David Stevens took the stand at an arraignment Monday. He is charged with two counts of murder in the Nov. 23 stabbing deaths of 23-year-old Samantha Wickenheiser, of Fargo, and 30-year-old Ward Berg, of Moorhead.

Judge Steven Marquart said he could not accept the plea because of concerns that Stevens fully understood what was happening in court. He ordered a psychological evaluation.

David Stevens’ wife told police the pair drove from Brookings, S.D., to Fargo because the suspect wanted to pick up clothing. David Stevens later told dispatchers he had brought a knife for protection.