Sandy looked up surprised she had someone watching and waved to him in sort of a "Don't worry" gesture.

Then, struck by inspiration she dug around in her backpack and drew out some chalk. This spot would be a great place to draw the outline of a body like the police do.

Why?

Because she's young and thinks it would look cool. She lets her stone skin melt back into flesh as she begins her work kneeling on the crumbled wall where there was space large enough.