Bahena Rivera partially confessed to stalking Tibbetts while she was out for a run, killing her and dumping her body in a cornfield.... He said they killed her and put her body in the trunk of his car and made him dispose of her.He didn't tell investigators about the men earlier in the inquiry because they threatened to kill his girlfriend and young daughter, he said.... Cristhian Bahena Rivera appears during a hearing at the Poweshiek County Courthouse in Montezuma, Iowa....