(NewsNation) Lindsay Polyak, the mother of a child taught by Andrew James McGann, who is accused of killing a married couple at Devil's Den State Park in Arkansas, tells "NewsNation" she is "absolutely shaken."Polyak joined "Banfield" on Friday night to discuss her perspective on the alleged killer, who allegedly admitted tokilling Clinton David Brink, 43, and Cristen Amanda Brink, 41,who were hiking with their two young children."I was just absolutely shaken that Cristen and Clinton Brink were brutally murdered, allegedly, by the hands of the man that my son was around every day at his elementary school," Polyak said. She explained that while McGann wasn't her son's regular teacher, the alleged murderer was occasionally in the classroom during Fridays.Devils Den suspect admitted to killings after DNA found, police say"It was chilling to realize that he was around someone who could do this," she added.Clinton Brink is believed to have been stabbed first. Cristen Brink rushed her young daughters to safety and was killed as she returned to help her husband, Arkansas State Police said."I saw him at school events, and he looked charismatic," Polyak said of McGann. "He looked like the kids enjoyed being around him, that they flocked to him."Polyak said there were "red flags," such as her 10-year-old mentioning McGann liked to "play tag at recess, he plays Truth or Dare with the girls."And then I start hearing these things like he's giving out candy. He gives candy out in class, but really, it's for the girls."