The sister of the man convicted in the racially motivated mass shooting at a Charleston church has been arrested for carrying a knife to her South Carolina school.

Morgan Roof, 18, was also charged for having pepper spray and marijuana, according to the local sheriff’s department. She has been transported to the local detention centre and a judge has set her bond at $5,000. She is not allowed to return to the school.

Investigators also said she posted a racially charged Snapchat on the morning of the national walkout calling for gun reform, but that this didn’t play a part in her arrest.

An screenshot, allegedly of the Snapchat, is circulating on social media, in which she appears to say that she hopes students “get shot” during yesterday’s national walkout protest calling for gun control.

“You are walking out for the allowed time of 17min, they are letting you do this, nothing is gonna chance what tf you think it’s gonna do?” it reads. “I hope it’s a trap and y’all get shot we know it’s fixing to be nothing but black people walkin out anyway.”

Her brother, Dylann Roof, is an avowed white supremacist who massacred black church-goers at a historically black church in Charleston in 2015. He pleaded guilty to nine counts of murder and three counts of attempted murder.

He was sentenced to death by lethal injection in 2017, and is currently on death row in Indiana.

Image: Richland County Sheriff's Department