Marshall Stewart has been searching for his son's killers since 1988
                                
                                
                                    (Newser) -
                                    "For thirty-five f—ing years, my brain's been turning over all these questions," says Sean Stewart. Questions like why the bodies of his 16-year-old brother, Shane, and Sally McNelly, 18, were left in the brush along a rough dirt path leading to a reservoir outside San Angelo...