Naruko had tried to steal the Forbidden Scroll of Seals.
She'd succeeded too, but only because Hiruzen had gone out of his way to allow it.
After all, he REALLY wanted to know who the fool that put her up to it was. So, while every available Chunin hunted the girl down, Hiruzen had watched the events unfold from the crystal ball in his office. He was glad to see that Naruko had gained something from this mess, and quickly signaled his Ambu to finish the job.
The Torture and Interrogation Force had broken Mizuki in under an hour.