The newspaper story doesn't really give the full background to the case, which is pretty horrific. The 12-year-old involved, Cristian Fernandez, killed his 2-year-old brother, and it is for that which he is in jail. However, Cristian's mother was only 12 herself when he was born, and his own father - in his late teens at the time - didn't play any part in Cristian's upbringing in Miami. His mother then got together with the father of her younger son, still living in Miami. The stepfather was abusive to the children, physically, emotionally and sexually, before at some point killing himself. At this point Cristian's mother decided to move away from Miami, and headed north to Jacksonville.
It was at some point after then that Cristian killed his brother.
The prosecutor then decided to try Cristian as an adult for murder - something which, as I recall, still attracts the death penalty in Florida. He's therefore being held in an adult prison, along with adult prisoners - and if you've seen any of Louis Theroux's recent series you'll have an idea what conditions in Florida's adult prisons are like.
The prosecutors seem to think this is OK because he's being held in solitary confinement. A child in solitary confinement? That's bad enough for an adult, but children need to be active and moving about. He's stuck in a 30 square feet cell, only allowed out for 1 hour a day (and there's no certainty that he's been able to have this yet.) The only window is being shaded to stop others looking in (which wouldn't be a problem if he was in a juvenile centre.) His mother is elsewhere in the jail on related manslaughter charges, but prison rules prevent them visiting each other.
The thoughts of the prosecutor? "If I were the parents of a kid charged with petty theft, I would be outraged if someone charged with first-degree murder were there right beside them"