According to the allegations, the mom was captured on video hitting her son at least 13 times. Records also show she allegedly had her son wear a dress to embarrass him.
Walker allegedly entered the school unauthorized and yelled at a 12-year-old girl and asked if the child had been bullying her child. Then, officials say, Walker threatened to shoot up the school.
Since the arrest of the teenage girls on Tuesday, investigators have been working to get a search warrant signed by a judge.
The police chief says the teens communicated on social media to plan the attack, and those communications were intercepted by the FBI.
The FBI says the plot involved pipe bombs and guns. The case spans two counties, with the girls attending two different Houston-area school districts.
An Indiana high school student has been accused of plotting a mass shooting at a school near Indianapolis on Valentine's Day, local police said Thursday.