The superintendent of Los Angeles public schools has resigned four months after he was put on paid leave during a federal investigation. The district's Board of Education announced Monday that it had received a resignation letter from Alberto Carvalho. It was effective as of Sunday. He had been on paid leave since February after the FBI searched his home and district headquarters. Carvalho had denied any wrongdoing and requested reinstatement. The investigation's details remain undisclosed and no charges have been filed against him. Andrés Chait will continue as acting superintendent.