A high school teacher from Hartsdale was arrested and charged in an online child predator sting.

The U.S. Attorney's Office says it arrested 34-year-old Kostas Fekkas in an undercover operation last year after an agent posed as a 13-year-old girl.

During those conversations, Fekkas was said to have asked the agent for photos of their body and sent over several explicit photos and videos - including one from inside a classroom.

Fekkas also allegedly told the agent posing as a minor that he had sex with a 10th grader once and would be willing to get involved with a minor again.

Investigators later searched his cellphone and found explicit photos and videos of a 12-year-old girl in a secret calculator app on his phone.

Authorities say Fekkas previously worked at schools in the Bronx and Westchester counties.

If found guilty, Fekkas faces a maximum sentence of 20 years in prison.

Anyone who believes they may have been victimized by him is urged to contact police at 1-866-DHS-2423.