Is it possible to establish custody of a child if the father is in mexico?

My mom brought my brother with her to the United States when he was only one. My brother is now 7 and my mom is trying to see if she could obtain his full custody, here in california, even though my dad is in mexico. My brother does not know my dad. My father has never given a penny towards the support of my brother and has a criminal background that includes from domestic violence to attempted murder.