NORTH PLATTE, Neb. (AP) – A North Platte man charged with second-degree murder in the death of his wife has been found competent to stand trial.  The attorney for 34-year-old Rogelio Diaz had asked for the evaluation. Diaz was seen by a state expert, and a judge ruled on Monday that Diaz was competent.  Police say Diaz killed 35-year-old Michelle Diaz in their backyard around 2 a.m. on June 25.  An ambulance crew found Michelle Diaz unresponsive. She died at a local hospital.  Police say Roger Diaz told officers his wife fell from the backyard steps, but he later changed his story.  Diaz is being held on $2 million bail. His attorney did not immediately return a call Tuesday.  A hearing is set Aug. 22.