Rosenstein was confirmed by the Senate 94-6. Mueller reports to Rosenstein.
https://www.washingtonpost.com/world/national-security/rod-rosenstein-confirmed-as-deputy-attorney-general/2017/04/25/e59bc3a8-29dc-11e7-be51-b3fc6ff7faee_story.html?utm_term=.8fc704766bba
Rosenstein was confirmed by the Senate 94-6. Mueller reports to Rosenstein.