A 44-year-old Brooklyn high school teacher previously arrested after allegedly using Snapchat to send a photo of his genitals to a 16-year-old student has been accused in a new 36-count indictment of victimizing six other teenage girls, authorities said.

Brooklyn Tech teacher Sean Shaynak pleaded not guilty last month to charges including dissemination of indecent material to a minor and harassment. The math and physics teacher was arrested Tuesday morning on the new indictment, which charges him with kidnapping, among other crimes, when he showed up for a court appearance in connection with the previous charge.

Prosecutors say Shaynak, a city employee for nearly six years who has worked at Brooklyn Tech for the last five, allegedly took a 15-year-old to a nude beach in New Jersey without her parents' consent, performed a sex act on an 18-year-old student without her consent and sent photos of his genitals to four students, including two minors. He also allegedly touched students inappropriately and kissed them, grabbed the buttocks of a minor and gave alcohol and cigarettes to others.

The indictment also alleges Shaynak terrorized a former student with whom he had a prior relationship. He's charged with menacing, reckless endangerment, kidnapping and committing a criminal sexual act, among other offenses for allegedly victimizing six girls, who range in age from 13 to 19, between 2011 and 2014.

Prosecutors say the indictment stems from a search warrant executed at Shaynak's home following his Aug. 26 arrest. Thousands of text messages, as well as hundreds of photographs and videos, were recovered from three computers and two phones seized during the execution of the warrant.

Shaynak was arraigned on the new indictment Tuesday. It wasn't clear if he entered a plea, nor was information on his attorney available.

Brooklyn Tech is one of the city's most selective public schools.

Mayor de Blasio's son, Dante, is a student there.

The Department of Education called the alleged behavior "unacceptable." It said the teacher was reassigned "effective immediately" and "is away from the school and children."