Tony Stewart was back in his comfort zone, behind the wheel of a race car. Will the brash racer they call ''Smoke'' regain the edge that made him a NASCAR superstar, even after conceding he'll be affected the rest of his life by the death of Kevin Ward Jr.? ''This is a sadness and a pain I hope no one has to experience,'' Stewart said in his return to the track Friday, ending nearly three weeks of seclusion after Ward's life ended under circumstances that are still hotly debated. ''That being said, I know that the pain and mourning that Kevin Ward's family and friends are experiencing is something that I can't possibly imagine.'' About the time Stewart was speaking, authorities in New York said that their probe into Ward's death will last at least two more weeks. More...