ORANGE CITY, Fla. -

A former Volusia County teacher was arrested Wednesday after deputies say she had sex with a 16-year-old student.

Stephanie Cobb, the 26-year-old former English teacher at University High School in Orange City, bonded out of jail Wednesday night after she was arrested on charges of unlawful sexual activity with a minor.

She refused to comment about her arrest.

The investigation started in December after deputies say they got an anonymous tip that the student at the school was suicidal. The tip said the student was sending suicidal text messages, but deputies said they found out the tip came from Cobb's cellphone.

Deputies checked in with the boy at school and he said he was fine, but they found out he was involved in a relationship with a teacher. According to deputies, they found Cobb's cellphone number in his phone as "my precious angel."

Cobb was confronted about the incident and resigned from her position after the investigation began, officials said.

Investigators said they talked on the phone more than 500 times and texted 12,000 times over a four-month period.

The teen said they first started talking about college plans but the relationship grew, deputies said. He said they were in love and told deputies he and Cobb had sexual relations.

Cobb was taken to the Volusia County jail in Daytona Beach, where she posted bond at $25,000.