Joint chief of staff?

As a detective, I approached the crossword clue ‘Joint chief of staff?‘ with my reasoning cap on. I knew that the phrase ‘joint chief of staff‘ referred to a military position, and had to think outside the box to discover a viable answer. With some brainstorming, it dawned on me that the word ‘joint‘ had to do with anatomy. For some reason, the term ‘warden‘ came to my mind, and upon examination, I realised that a “joint” could refer to a hinge, and a “warden” is a person in charge of a facility or institution, typically a prison. Therefore, a warden could be considered a “joint chief of staff” in relation to running a prison. Alas, the crossword puzzle had been solved!