By JIM SALTER
ST. LOUIS (AP) — A witness whose testimony helped send a man to prison for a killing decades ago has testified his role in the case of Lamar Johnson “still haunts” him. Johnson has contended from the outset that he had nothing to do with the 1994 killing of Marcus Boyd. St. Louis Circuit Attorney Kim Gardner believes Johnson. She filed a motion in August seeking to vacate his conviction in the 1994 murder of Marcus Boyd, allegedly over a $40 drug debt. The Missouri Attorney General’s Office argues that evidence still points to Johnson as the killer. The man who named Johnson from a lineup, James Gregory Elking, says he was coerced into doing that.