According to an article I read: "Johnson was 28 years old, in a difficult marriage headed toward divorce, and unemployed. She was at the office to sign over custody of her 12-year-old son to her mother, with whom he'd been living. Her mother had hired Moore to handle the custody petition."
Why would any mother give up custody of her only son? I have two sons, and never would have signed custody away to my mother, despite the fact that my mother was a wonderful woman. It sounds to me like she wanted to get rid of responsibility for the boy. It also sounds like the son was from another marriage, or had been born out of wedlock. The boy was possibly living with the grandmother because there was a problem with the then-husband's relationship with his 12 year old step-son.
Thanks for the info.
Most likely drug addiction.