Hi,
i am in the Human Resources field and i know a bit about the Labor Laws, working, working standard and working illegally. As long as work is performed he must be paid... Although he is an undocumented worker he is entitled to the same protection and Fair Labor Standards (FLSA) laws as any citizen. He can actually file a complain with the Department of Labor (DOL) for unpaid wages... i am 100% sure he will get the money he is owed... Actually his past employer may face legal issues with this regards.. Don't be scared that he worked illegally or not. i believe his ex employers know his situation and they are thinking they can get away with free labor.. Please, go get the money.. YOU NEED IT and it is totally legal..