Christian Karl Gerhartsreiter, the man once known as Clark Rockefeller, appeared Wednesday in Los Angeles Superior Court, where his Boston-based lawyers provided a glimpse of how they will defend him against charges that he killed the son of his landlady. Brad Bailey said he and his cocounsel, Jeffrey Denner, alerted the court that they may introduce another possible suspect who could have killed John Sohus, a 27-year-old computer programmer who lived in the San Marino, Calif., home where Gerhartstreiter was a tenant in the early 1980s. Bailey declined to specify who they would cite as the other suspect. Bailey said the attorneys are also likely to file a motion to suppress statements Gerhartsreiter made to the press after he was arrested in 2008 in the kidnapping of his daughter.