(Portland, OR)  --  Arraignment is scheduled today for a man accused in the disappearance of a Salem mother and her three-year-old son.  Police arrested 52-year-old Michael Wolfe at a Blue Star Donuts store in Portland Friday on two counts of aggravated murder and two counts of first degree kidnapping.  Police say he's the biological father of three-year-old Billy Fretwell, who was last seen May 13th along with his 25-year-old mother, Karissa Fretwell.  Police are still searching for the two but say they have probable cause to charge Wolfe with murder.  KATU reports Fretwell and Wolfe were engaged in a custody battle for Billy.