FERGUSON WITNESS . . . THE CHIP MADE HIM DO IT

Acting as his own defense attorney in a bizarre trial, the man accused of murdering six people in a shooting spree on a Long Island commuter train wrapped up his case today by telling the jury that survivors of the massacre conspired with police to implicate him. Colin Ferguson''s closing argument came after the judge refused to permit testimony from a defense witness who allegedly told the prosecutor that authorities used a remote-controlled computer chip in the 37-year-old defendant''s brain to manipulate his behavior. Charged with shooting 25 people on a crowded train in 1993, Ferguson Ñ who is black Ñ simultaneously has claimed his gun was stolen by a white man who went on a rampage, that the killer was a black man who looks like him and shares his name, and that he is the victim of a murder conspiracy linked to the prison slaying of serial killer Jeffrey Dahmer. Ferguson called just one defense witness, a detective who already had taken the stand during the prosecution, when a dozen victims testified that Ferguson shot them.