A new trial date has been set for the man accused of the abduction and stabbing death of 20-year-old Mollie Tibbetts in Brooklyn.  On Friday (2/1), a judge set trial for 24-year-old Cristhian Bahena Rivera on September 3 in the Poweshiek County courthouse in Montezuma. Trial had been set for April 16. Defense attorneys said they needed more time to go through a massive investigation file from prosecutors. Rivera is charged with first degree murder in the killing of Tibbetts, a University of Iowa student who disappeared while out for a run July 18 in her home town of Brooklyn. Investigators recovered her body a month later in a cornfield. A medical examiner has said Tibbetts was stabbed to death.  Rivera is a Mexican national who has been accused of being in the country illegally. He worked at a dairy farm a few miles from where Tibbetts disappeared.