Svetla Clancy's son, who wandered away from his Wake County school

CARY, N.C. (WTVD) -- A Cary mother is demanding her son's principal be fired after the kindergartner slipped out of Carpenter Elementary School last month and was spotted walking down a busy highway.Svetla Clancy said a substitute teacher at the school allowed her 5-year-old son to go to the bathroom alone. Instead, the boy decided to walk home.He left the school through the front door, unnoticed, and walked to Morrisville Parkway.Clancy said a family friend later saw the boy walking along Louis Stephens Drive and drove him back to school."He was missing for 20 minutes, and when she brought him back no one knew he was gone. They had no idea," said Clancy.Clancy said the school's principal called her about an hour later and told her the boy left through a side door at the school but was quickly guided back in by an adult."She made it sound like it was something that he did wrong. Once I found out a 7 o'clock at night, that was the worst day of my life, because I immediately went to what if it wasn't her, what if he crossed [the street]" said Clancy. "I was enraged. I was very upset. I cried in front of my child. My husband couldn't console me."Clancy contacted the superintendent who launched an investigation."The school takes full responsibility for the incident and has taken immediate action to ensure the safety and well-being of all students," said WCPSS spokesperson Lisa Luten.The district said the following new procedures have been put into place:According to WCPSS, the substitute at the center of the incident was suspended without pay but is still in the pool of possible fill-ins.Clancy told ABC11 she believes there is a lack of accountability.She has started a petition demanding the school's principal be terminated."I'm advocating for our kids here because I want to make sure nothing like that happens again before it's too late, before a kid actually does get hurt," said Clancy.