Juanneika Scott was devastated by the shooting death of her 19-year-old son Mykal Prime on July 25.
Metro police are still investigating the circumstances surrounding his death.
Khadijah Griffis, 25, told police she shot Prime with her own gun in self defense while she was selling him marijuana in the parking lot of the Marathon market on John A. Merritt Boulevard.
After grieving for several weeks over their brother's death, Scott's 14 year old twins went back to school last week. "I put them in a safe place. I thought the school was safe," Scott said.
But that feeling of safety was shattered Friday when the twins had a substitute teacher in their math class. It was Khadijah Griffis, the same woman who had shot and killed their older brother last month.
"They were put in the room with their brother's killer and they were tormented by this woman," Scott said.
Scott said other students at the school actually knew Griffis because she had been a substitute there before. She said some students even asked her how she had gotten away with shooting someone.
Daquan Prime, 14, told us he looked up her up online and suddenly realized who was teaching his class.
"I was putting two and two together and I was like that's my brother's killer," Prime said. He said Griffis kept calling his name and claimed that she taunted him.
"She kept on mimicking my name, and kept on taunting it. She kept saying Daquan Prime," Prime said.
The twins attend RePublic High School which is a Metro charter school that uses two temp agencies to fill substitute teaching positions. Scott cannot believe Griffis was hired despite numerous news articles about what happened.
"If they Googled her, they'd find out she had guns and drugs. A school teacher? I never heard of a school teacher like that," Scott said.
Jon Rybka is the CEO of RePublic Charter Schools which operates the high school and other three middle schools in Davidson County.
"As soon as we found out what happened we obviously immediately asked her and escorted her off the premises," Rybka said.
He said Griffis was assigned to RePublic by a New Orleans based temp agency called Enriched Schools, which provides substitutes to charter schools across the country.
"We immediately contacted Enriched and asked for an explanation of what happened here," Rybka said. Rybka said fellow teachers had sent Enriched Schools news articles about the shooting, and the company "red flagged" Griffis.
But he said somehow that hold got lifted and she was allowed back in the classroom.
Juanneika Scott held her kids out of school this week and said she wants changes in how they vet their substitutes.
"If a red flag ain't working what other security measures need to be done?" Scott said. "I feel like I let my kids down when I sent them to school that day."
Rybka said he and the school principal have met with Scott and apologized about what happened.
He said RePublic Schools will stop using Enriched teachers going forward until they get assurances this will not happen again.
NewsChannel 5 Investigates called Enriched Schools, but did not receive a call back.