Christian Choate was found buried under concrete in a trailer park.
Prosecutors say his father, Riley Choate, and his stepmother, Kim Kubina, starved and beat the boy and kept him in a cage.
The Northwest Indiana Times reports the boy wrote letters about how he wanted to be liked by his family and how he wanted to die. The letters were discovered after his body was found.
Choate's father and stepmother have pleaded not guilty to murder and abuse charges. The Indiana Department of Children Services put out a statement saying: "With regard to these circumstances DCS did everything it legally could to ensure the well-being of this child at the time of our interactions with the family."