How can I obtain Custody?

[weebecci]

I am only related to my 14 year old nephew by the birth of his brother and sister with my biological brother. My nephew's mother and my brother were never married and My (I call her anyway) Sister in law killed herself in May at her parents home that all of them shared. My nephew is still living with the grandmother who is addiceted to presciption medication as well as her boyfriend (commonlaw husband I think) and his biological father has not been heared from since prior to his birth. His mother and he were never married either. They do not have any income what so ever, and seek assistance from the state by a letter written prior to the mother's death stating she could have guardianship there even though she was there as well. The letter was handwritten and never notorized or addressed with the court. The grandmother has no actual "legal" guardianship nor custody of my nephew. He has asked many times to move back in with me as he did for a year when he was approx. 8 years old. How and can? I obtain custody of him in some way?