A Coweta County teenager was arrested on child pornography charges after he allegedly blackmailed teenage girls into sending him nude photos of themselves.

Geovanni Jacob Adamson, a 17-year-old former student at Newnan High School, is facing 21 counts of child sexual exploitation, 2 counts of child pornography and one count of computer theft.

Police said at least 17 girls, most of whom are students at Newnan High School, received threatening messages through email and social media from an individual who claimed to have hacked their social media accounts and stolen nude photos of them. The hacker threatened to expose the photos on social media if they didn’t supply him with more.

JOIN THE DISCUSSION: The AJC's crime and public safety Facebook group is your source for breaking news

Sgt. Jim Beneke of the Newnan Police Department said most of the girls ignored or blocked the sender, but at least three complied with his demands.

“He threatened them with violence on their families,” Beneke said.

Beneke said Adamson didn’t actually have nude photos of the girls he threatened, but instead took photos that were publicly viewable on the girls’ social media accounts and photo-shopped them to make the girls appear nude.

VIEW: Map of crime in metro Atlanta

Know what's really going on with crime and public safety in your metro Atlanta community, including breaking news, trial coverage, trends and the latest on unsolved cases. Sign up for the AJC's crime and safety newsletter delivered weekly to your inbox.

The 17 known victims included both middle and high school students, the youngest of which is 12 years old.

Beneke said Adamson was in the process of transferring to Winston Dowdell Academy, an alternative education program, when he was arrested last Tuesday.

Adamson is being held in the Coweta County jail. His bond hearing is scheduled for Friday.