Mollie Tibbetts, a 20-year-old sophomore at the University of Iowa, was last seen alive while jogging the evening of July 18. This week, authorities said that she was killed and that her body was dumped in a cornfield. On Tuesday, the police arrested a Mexican immigrant named Cristhian Bahena Rivera as a suspect. A warrant filed by the Poweshiek County Sheriff's Office said Rivera confessed to the police that he pursued Tibbetts and later concealed her body. The police charged Rivera with first-degree murder, which in Iowa comes with a possible penalty of life in prison. By Wednesday, law-enforcement officials...