Yes, she says "Where is she, Steven? WHERE IS SHE?"
And Steven looks toward her, then looks away dismissively...then as he's exiting, it appears he puts his hand palm up in a shrugging, "I don't know" gesture.
He's just awful, he will never in a million years come clean about what he did. I think he's impulsive, dumb, and kind of fatalistic/apathetic.
So grateful that the jury convicted him of the murder and of the enhanced sentencing for exceptional cruelty. Nothing can bring Charli & Joshua back, but it's so awesome that justice was served in this horrible case. He will never see the light of day again. Nothing but love and respect for those jurors, they did good.
Regarding his aunt bringing him drugs in prison...apples don't fall far from the tree in his family, apparently. They all seem to make really poor, ill-thought-out decisions. I remember someone posting that the aunt would show up to court to support Steven and give flippant looks to Charli's family. :-(