Wal-Mart Stores Inc. (WMT) apologized after a highway accident involving one of its truck drivers critically injured actor-comedian Tracy Morgan and prompted the U.S. National Transportation Safety Board to join a state investigation. Kevin Roper, 35, of Jonesboro, Georgia, was charged in Middlesex County, New Jersey, with one count of death by auto and four counts of assault after the Wal-Mart tractor trailer he was driving crashed into a limousine van whose occupants included Morgan. The six-vehicle accident, at 1 a.m. yesterday on the New Jersey Turnpike, occurred as U.S.