- 07.03.13 06:08 PM EDT
The post said: "I think Ima shoot up a kindergarten/ And watch the blood of the innocent rain down/ And eat the beating heart of one of them."
His parents say their son wrote "jk" at the end of the comment and was responding sarcastically. They said the teenager, who has been imprisoned since the arrest in February, has been beaten and abused in jail. Carter could spend up to 10 years in prison if he's convicted at a hearing on July 16.