BLYTHE, Calif. (KESQ) - A Riverside County sheriff's deputy accused of searching a secure computer network without permission or a legitimate reason pleaded not guilty to felony charges, court records showed today. Matthew Enrique Estrada, 53, of Blythe was arrested in May following a nearly yearlong probe by the Riverside County Sheriff's Department's Special Investigations Bureau. Estrada is charged with two counts of unlawfully accessing pr…