Gov. Haley Barbour announced Aug. 29 that the Department of Public Safety was conducting its own internal investigation after authorities were told about possible impropriety in testing procedures.
On Tuesday, the Mississippi Central Troopers' Coalition is holding a news conference at the state NAACP headquarters in Jackson to call for the independent probe.
In February 2009, the NAACP filed a complaint with the U.S. Equal Employment Opportunity Commission on behalf of Mississippi's 200 black troopers. In July 2009, the EEOC said it found evidence of discrimination and forwarded those findings to the U.S. Justice Department.