A Fulton County convicted sex offender is back behind bars after apparently breaking his probation rules.

Fulton County School Officials said Demetrius Thompson was serving as a volunteer parent for the Bear Creek Middle School and Creekside High School band programs.

The Fulton County Sheriff's Department said Thompson went on several field trips and was around children on multiple occasions.

Bear Creek Middle School parent Bobby Wilcox first realized the problem as he looked at the Georgia Sex Offender Online Registry Monday evening.

He was amazed when he said his Fairburn neighbor's picture popped up.

"When I first showed them the picture, my daughter was like 'Daddy, that's the guy that was passing pizza out to us at the football game,'" Wilcox said.

Wilcox called the School Principal the next morning and the district immediately banned Thompson from any school property.

Fulton County Sheriff's Deputies then got involved with an arrest warrant for Thompson for violating his probation. He was convicted in 2004, records show, on two counts of aggravated child molestation.

When Channel 2's Tony Thomas went to the door of the Fairburn house authorities said Thompson had been living in, someone shouted out the window, "I need you to leave now!"

A couple hours earlier, deputies had knocked on the same door trying to serve an arrest warrant.

Investigators said Thompson turned himself in to the Fulton County Fugitive Squad Tuesday evening.

A school district representative told Thomas that Thompson passed the background check because he falsified information on his application, changing his name so it didn't match the sex registry information.

The school district sent out an automated telephone call and email to parents Monday night saying: "This is your principal Darron Franklin. As you know, I make every effort to maintain open and honest communication. Today is no different. I do not want you to be alarmed, but today, I learned some disturbing news that I'd like to share with you. It has been confirmed that one of our parent volunteers is on the sex offender list.

"Fulton County School police immediately notified the parent that they are banned from all school campuses, and that parent's probation officer was notified. School staff also checked the sex offender registry for all surrounding municipalities for all guardians and emergency contacts at our school. We take this matter very seriously.

"Our main priority is the safety and well-being of each student. The school system will immediately review the volunteer approval process to make sure this doesn't happen again.

I am confident that Bear Creek Middle is, and will continue to be, a safe place for your child to learn."

For Wilcox, one time is a time too many.

"He was in there freely, doing whatever, smiling at people. The audacity is really just what made me angry," Wilcox said.

Fulton County School District leaders said they are trying to get equipment that would scan a person's ID and match it to the database every time they come on school property.