( CNN ) -- Mexican authorities have arrested a former college professor who was on the FBI 's 10 most wanted list over allegations of child sex abuse . Walter Lee Williams was detained late Tuesday , Mexican state news agency Notimex reported . The FBI placed the former university professor wanted for alleged sexual exploitation of children on the list Monday , according to Notimex . Williams researched in the field of gender development at a university in California , which gave him easy access to his victims , mainly teenage boys in developing countries , the FBI said . Agents believe he had resided in Indonesia , Polynesia and Thailand , but also may have traveled to Mexico and Peru . An FBI agent reported finding child pornography on a computer and in a video camera belonging to Williams . He was the 500th suspect added to the `` FBI 10 most wanted fugitives '' list , and the bureau offered $ 100,000 for information leading to his arrest . Williams ' photo had appeared in Mexican newspapers identifying him as a fugitive . Police arrested him in a cafe in Playa del Carmen after he failed to produce proper identification .
Walter Lee Williams was a professor studying gender development . He had easy access to his victims , mainly teenage boys in developing countries . The FBI offered $ 100,000 for information leading to his arrest . It believes Williams lived in Indonesia and Thailand and traveled to Peru and Mexico .