A Watsonville man has pleaded not guilty to fatally stabbing his brother. 38 year-old Seledonia Diaz is accused of killing his 55 year-old brother on Delaney Avenue March 30th. Diaz is charged with felony murder….and enhancements including use of a deadly weapon in the commission of a felony, serious felony violation and prior serious felony strike. He is set to return to a Santa Cruz County Courtroom July 22nd.