RALEIGH — A Confederate monument in Charlotte has been vandalized for the second time in three weeks, police said Tuesday.

The names of eight of the nine people killed in the mass shooting inside a historic black church in Charleston, South Carolina, were spray painted on one side of the monument. Shooting victim Ethel Lance’s name was not included.

The phrase, “The cause for which they fought — the cause of slavery — was wrong,” was spray-painted on the other side of the granite monument, which was first unveiled in 1929.

No one has been charged and the investigation is ongoing, said Charlotte-Mecklenburg police spokesman Keith Trietley. Police believe the monument was vandalized between 11 p.m. Monday and 9 a.m. Tuesday.

On July 16, liquid cement was smeared on the monument, which was cleaned at Mecklenburg County’s expense.

The monument’s inscription gives “grateful recognition” to the Confederate soldiers who “preserved the Anglo-Saxon civilization of the South.” The granite monument also features four Confederate battle flags.

The vandalism comes as the nation debates the appropriateness of the Confederate battle flag and Confederate monuments after the shooting of nine worshippers at ‘Mother Emanuel’ AME Church in Charleston, South Carolina. The suspect in that case, a white man, posed with the Confederate flag in photographs.

Last month, South Carolina removed the Confederate battle flag from its statehouse grounds but left the Confederate memorial standing. Also in July, North Carolina passed a law banning state or local authorities from removing “objects of remembrance” — including Confederate monuments — from public property without state legislative action.

The Mecklenburg County monument was one of two monuments vandalized in Charlotte on July 16. The word “racist” was spray-painted on a memorial at Old City Hall. The city removed the monument and relocated it to a city warehouse for cleaning, where it remains.

“The city is still working to determine the most effective and cost-efficient measures to clean and repair the monument,” said corporate city spokesman Ken Brown. “Considering the possibility of repeat acts of vandalism, the city is also exploring measures to apply a protectant.”

The Old City Hall monument was donated by the Confederate Memorial Association of Charlotte in 1977. The United Confederate Veterans raised funds with Charlotte citizens to pay for the Mecklenburg County monument.