Cohen, who has served in the state legislature for more than 15 years, was accused last week after two of his Democratic colleagues and officemates alerted authorities that they suspected he had downloaded child pornography onto a computer in the Union Township legislative office they shared.
After an investigation was begun and authorities confiscated his computer Wednesday, Cohen checked himself into a hospital for psychiatric evaluation, and this morning he submitted his resignation.
"Please accept this letter as my formal resignation from the General Assembly of the State of New Jersey, effective immediately," his one-sentence resignation letter read.
Though no charges have been filed against Cohen, Assembly Speaker Joseph J. Roberts Jr. (D-Camden) accepted his resignation. "The allegations made against Assemblyman Cohen, if true, are sad and indefensible," Roberts said in a written statement.
The State Police's official corruption unit and its digital technology investigations unit will continue its investigation, law enforcement officials said, and will report directly to the state Attorney General's Office.