"Did you kill your brother?"
"No!"
"Are you sure?"
"Yes!"
"Yeah - are you really sure?"
Clearly, the actors don't know what to say so they just keep asking suspects if they're sure. If that's a real interrogation technique, the police must get a lot of suspects laughing in their faces.
"Oh wait. Maybe I'm not really sure if I killed my brother this morning. Let me think about it." (giggle)
