CHICAGO (CBS) — Prosecutors in Lake County have launched an investigation into revenge porn allegations waged against former Illinois State Rep. Nick Sauer, who allegedly sent nude photos of an ex-girlfriend on Instagram.

Communications manager for the Lake County state’s attorney’s office, Cynthia Vargas, confirmed the investigation is ongoing.

“We were contacted by the inspector general on July 31, and have since launched an investigation,” Vargas said.

The freshman lawmaker—a former member of the House Sexual Harassment and Discrimination Task Force–was in his first year in the legislature when revenge porn allegations came to light on July 31–bringing his career to a premature end.

Rep-Nick-Sauer-resigns

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A Politico story broke news of the allegations that Sauer used a fake Instagram account to send private photos of his ex-girlfriend, Katy Kelly, to other men.

Sauer, according to the allegations, lured the men into thinking they were chatting with Kelly, and coerced them into “engaging in graphic conversations of a sexual nature.”

Sauer resigned Wednesday afternoon, a few hours after the accusations were made public. By then, Republican lawmakers—including Illinois Governor Bruce Rauner—had begun calling for him to step down.

“As a result of the allegations by Kate Kelly, a former girlfriend,” Sauer wrote to the House Clerk. “I have decided to resign my office. It is important that the citizens of the 51st District be fully represented.”

The complaint is being handled by prosecutors from the special investigations unit, the Lake County state’s attorney’s office.