COBB COUNTY, Ga. -- A Cobb County teacher has resigned after being arrested for allegedly stalking a former student.

Joseph Placanica told police he and the 17-year-old did have a sexual relationship at one time.

Placanica quit his job teaching science at Durham Middle School hours after his arrest. Police said the 40-year-old teacher claimed he had a relationship with a former student that started when she was 16-years-old.

VIDEO: Cobb Teacher Accused Of Stalking Former Student

"What we do know is that he did take this juvenile out of state. At that time, apparently he was carrying on a relationship with her and it wasn't until April of '08 where she decided that she did not want to see or have anything to do with him," said Sgt. Dana Pierce with the Cobb County Police Department.

When the 40-year-old married teacher showed up at the Gold's Gym where the woman worked, she called police.

Placanica was charged with stalking.

"This is the result of unwanted e-mails, text messages and also, apparently she had a MySpace account that he has been on," said Pierce.

Some parents said the situation points out how carefully they must watch their children. "I get e-mails from the school, I have MySpace myself, I check their MySpace's, I know their passwords, I can't imagine that getting past me," said one student's mom.

Placanica has been released on bond.