Can a non-us citizen co-sign for a mortgage or auto loan?

I know someone who says that she was the co-signer for the mortgage and an auto loan from her previous marriage. She has a work visa but isn't a US citizen. She says the she is the one who had to sign to get the car and her house because her ex husband whom she was married to at the time had bad credit. Is it even possible for a non-us citizen to be on a loan like that? Her employment at the time was an ociate's posititon at wal-mart, part-time, and the ex husband I think made around 40-50 K per year.