Denial
Instead of coming clean and recognizing that he made a mistake, the boy told the police that he didn’t know anything about the rock. He lied and stated that he went to the formations with his friends that day, just to go on a hike and nothing more. Shortly after, they let him go.
There was nothing they could catch him on yet, the police didn’t have any concrete evidence. But just from his reaction after they mentioned the rocks, they knew that he had been up to no good. But how on earth were they going to connect him and his friends to the scene of the crime?