Black advocate and author Anthony Hervey died on the way home from pro-Confederate-flag rally

The Mississippi Highway Patrol is investigating the car crash that killed a black man who was an advocate for the Confederate flag, PEOPLE has confirmed.

“Our accident reconstruction team is reviewing information at this time [and] also interviewing witnesses with anything, as far as retaining to the crash,” Lt. Johnny Poulos of the Mississippi Highway Patrol told PEOPLE.

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“We’re hoping the investigation will be completed in the next few days, we’re just tying up some loose ends,” he added.

Anthony Hervey, 49, author of Why I Wave the Confederate Flag: Written by a Black Man, died on Sunday on his way home from a pro-Confederate-flag rally in Alabama, the The New York Times reported.

Arlene Barnum, 60, a fellow speaker at the Monumental Dixie rally, was in the sports utility vehicle at the time of the incident, the McAlester News-Capital reports. She told investigators that Hervey swerved on the highway then flipped over several times while trying to avoid a car that had pulled up beside them. Barnum also told investigators they were being chased.

When Hervey and Barnum’s car came to a stop, she tried talking with him, but he didn’t respond. It wasn’t until the pair reached the hospital that she’d learned Hervey had died, according to the The New York Times. Barnum suffered some cuts and a fractured foot.

Barnum has documented some of the chase on her Facebook page. She also posted a video from her hospital bed.

The Confederate flag has been a source of racial tensions for decades. Supporters say it’s a symbol of the South, but opponents argue it’s racist and represents slavery.

Racial tensions have peaked in the region since nine African-Americans, including prominent South Carolina state senator Clementa Pinckney, 41, were killed in a historic Charleston church in June when a white gunman, who appeared to have been influenced by the Confederate flag, allegedly opened fire at a prayer meeting.

Shortly thereafter, the South Carolina state legislature voted to remove the flag from the State House grounds, where it had flown since 1961.