Okay so what you are describing here is a very poor ability of impulse control. So let's take that as well as the video tapes of the squirming child who runs his mouth blabbering away talking to the Social Services worker.
You are John and Patsy Ramsey. You have just spent an entire night staging a murder to protect this kid who can't sit still, runs his mouth, and has such poor impulse control he just killed his sister in a fit of rage. This has been a pretty elaborate task, composing that ransom note alone took a couple of hours. Now you have the police and a group of friends at your house waiting for a phone call you know is never going to happen. One of them says to you - "Hey, let me take Burke over to my house to stay with my kids. My Aunt will watch him."
Is your immediate reaction "Sure, I know I can trust Burke won't say anything he shouldn't over there." Or do you think "No, I need to keep Burke here so I can make sure he doesn't talk to people and say what he knows."
Does that make sense to you?