Kenneth Palmer, a 22-year-old from Randolph, shot videos of himself masturbating in hallways at Jefferson Elementary School. He was charged in Essex County with criminal sexual assault for engaging in a criminal sexual act with himself in view of children under 13.
It was not known whether children had actually seen Palmer, but he can still be charged even if he is not observed, authorities said.
Palmer also shot a so-called "upskirt" video of a young girl at the school.
Palmer was arrested on an unrelated matter Sept. 28, 2017, at the ShopRite in Succasunna. The videos were discovered on his phone during the investigation by the Morris County Prosecutor's Office.
Palmer pleaded guilty in October to multiple counts of sexual assault by contact and one count of endangering the welfare of a child.
Under the No Early Release Act, Palmer must serve at least seven years.
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