How can I find out who owns the apartment complex my friend is renting?

my friend asked me to find out what bank owns the apartment rental she lives in. it is a huge complex in michigan. with over 1,ooo. apartments. it has changed hands from management to management over and over again. but who owns it? is my question. the manager would just say the bank but what bank? they won't give us any inforamtion she would like to make a complaint directly to the owners. but how do we find them on the internet, what public office can i refer her to?