Key dates in two murder cases in Placer County with local connections have been pushed back. The trial for Lee Konnerth, originally set to start Feb. 25, has been pushed back to May 14, said Placer County Deputy District Attorney Dave Tellman. Konnerth has pleaded not guilty in the May 15, 2011, shooting death of his fiancee, Sarah Ann Burr, who was pregnant with his child. Burr graduated from Nevada Union High School in 1999 and had been employed at Golden Empire Convalescent Hospital in Grass Valley since 2000. Placer County Sheriff’s deputies had responded to Konnerth’s house in Weimar …