Bruce Newman, Associated Press
In this May 8, 2000, file photograph, Anthony Hervey holds a Confederate flag while standing underneath the Confederate monument in Oxford, Miss. The Highway Patrol says 49-year-old Hervey was killed Sunday, July 19, 2015, when his 2005 Ford Explorer left the roadway and overturned on Mississippi Highway 6 in Lafayette County. Hervey, of Oxford, has drawn attention over the years for opposing efforts to change the flag. He said he dressed in Rebel soldier garb to honor blacks who served with the Confederacy during the Civil War.

JACKSON, Miss. — Mississippi Highway Patrol investigators are trying to find people who might have been involved in a road dispute just before a crash that killed a black supporter of the Confederate flag.

Authorities say Anthony Hervey of Oxford died Sunday when he swerved a Ford Explorer off a north Mississippi highway. The vehicle landed upside down.

The SUV's owner, Arlene Barnum of Stuart, Oklahoma, survived. She says she let Hervey drive, and she was in the passenger seat.

Barnum says before the wreck, Hervey sped up to avoid a silver car carrying four or five black men who appeared angry at him.

Barnum couldn't identify the type of car or give a license plate number.

Investigators on Thursday requested the public's help in finding the car, but said another witness couldn't confirm another vehicle was involved.