Authorities say the abuse took place in the couple's south Los Angeles apartment.
Police say Brown and Mathews tried to hide the abuse by bringing a friend's healthy child to an appointment with the department of children's services.
It was during that appointment that a stranger found the boy abandoned and called police.
"In my time in policing, in 27 years, I have never seen anyone with these kinds of injuries that has lived," said LAPD Chief James McDonnell. The boy remains hospitalized.
If you have any information on this case, you're asked to call the LAPD at 1-877-lawfull. That's 1-877-529-3855.
