A former Cobb County teacher is accused of having sex with a student, who then extorted money and an "A" in order to keep quiet, Smyrna police said Friday afternoon.

Both the 55-year-old teacher and the student, a 17-year-old girl, will face charges, Officer Michael Smith said.

Jonas Magdangal, of Smyrna, allegedly drove the teen, whose name was not released, to the Comfort Inn & Suites on Highlands Parkway on Dec. 31, police said. At the Smyrna hotel, the two allegedly had sex.

After the encounter, the teenager allegedly extorted money and a better grade from Magdangal in exchange for not reporting the incident, according to police. At the time, the man was a math teacher at Campbell High School.

But the girl apparently told another student, who reported the information to an adult who contacted police, Smith told the AJC.

On Friday, officers secured an arrest warrant for Magdangal on a sexual assault charge. The student, who will be charged with extortion, was expected to turn herself in later Friday, her parents told police.

Magdangal was in his first year teaching at Campbell, and he resigned from the Cobb County school system March 16, a district spokesman told the AJC. Prior to Campbell, Magdangal taught math for four years at nearby Osborne High School, according to his resume posted online.