IOWA CITY, Iowa (AP) — The Mexican man charged with killing an Iowa college student was known for years on the dairy farm where he worked by another name: John Budd. Yarrabee Farms is facing scrutiny over whether its managers had any idea that Cristhian Bahena Rivera was in the country illegally before the slaying of Mollie Tibbetts.

The name under which Rivera worked for the last four years was confirmed by three people with knowledge of his employment history who spoke on condition of anonymity. The company declined to confirm or deny the alias. An immigration lawyer advising the farms says companies cannot discriminate against workers based on how their names sound.

Farm officials say Rivera presented an out-of-state photo identification and a Social Security number when he was hired in 2014.