That kid who was asking if he would be done in time for 6th period understood what his rights were?
Even after being in jail for awhile, he's asking his Mom if he will be home for WrestleMania. To me, he clearly lacked the cognitive ability to understand his circumstances at all.
I'll defer to your legal expertise, but that was disturbing to me.
No one would ever confuse him with a Rhodes Scholar.
Being an idiot, he could've conceived that he'd get help from the investigators once he shared some unpleasant facts. Indeed, investigators usually give a very vague promise of help if the interviewee just tells the truth. The interviewee isn't sure of what the help would be, but here perhaps hoped it included going home that day.