WHERE IS Carl Alfred Eder? On Dec. 12, 1958 the 16-year-old butchered five members of the Pendergast family of El Cajon, California. Father Thomas Pendergast had picked him up hitchhiking the month before, the boy said he was homeless so the kind man took him in until he got a job. That decision would cost Pendergast his family. Thomas was at work when the massacre occurred. Eder told detectives that Diane Pendergast, 4, was bothering him and he exploded in rage. He threw the child against a wall, then grabbed a gun and shot the mom, Lois Pendergast in the head. Cops say the crazed teen grabbed a knife from his 