Morgan Roof (4/23/2018 copy)

Mugshot of Morgan Roof, the sister of Charleston church shooter Dylann Roof, after her arrest outside Columbia on weapons and marijuana charges on March 14. Alvin S. Glenn Detention Center/Provided

COLUMBIA — Prosecutors dropped a marijuana possession charge Monday against the younger half sister of Charleston church shooter Dylann Roof in her first court appearance since posting a hateful social media comment last month about national school protests over gun violence.

But 18-year-old Morgan Roof still faces a charge of carrying a weapon on a school campus after teachers at her Columbia-area high school told authorities they found her with a knife, pepper spray and marijuana. The weapons charge is pending in state court.

The marijuana charge was dropped during a brief hearing before a magistrate. No reason was offered publicly. Roof, flanked by two Columbia lawyers, didn’t speak during the hearing.

She declined to comment afterward.

Roof was arrested during a search last month at A.C. Flora High School after she was confronted about a post she made on Snapchat, authorities said. The post, sent the morning of the national school walkout, criticized the nationwide protests held in the wake of a mass shooting at a Florida high school, authorities said. 

"Your (sic) walking out for the allowed time of 17min, They are letting you do this, nothing is going to change what (the expletive) you think it’s gonna do?" she wrote. "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 lawyer, John Delgado, denied that she was making a threat with her Snapchat post.

"It was an 18-year-old in the middle of a difficult day making a misstatement," he said. "It certainly wasn’t a threat."

Roof has no prior criminal history. A court date for her weapons charge is not scheduled.

Dylann Roof was sentenced to death in 2016 for the racially charged mass shooting of a pastor and eight parishioners at Emanuel AME Church.

Follow Joseph Cranney on Twitter @joey_cranney.

Joseph Cranney is a reporter based in Columbia, covering state and local government. He previously covered government and sports for newspapers in Florida and Pennsylvania.